Having trouble with nvim-lsp and autocomplete.nvim (very slow)

Hello, I am new to nvim-lsp and neovim 0.5 in general. My primary language server is tsserver. Sometimes (not always), after going to normal mode, it would take a couple of seconds (5, and sometimes even longer), to show diagnostics and/or errors (I check with LspInfo regularly, and the tsserver is always attached). On the autocomplete side of things, again, it takes more than a couple of seconds, to show up snippets, be it object properties, or anything else.
So what I wanted to ask was, is this a problem with my system? Or with my configuration. If the latter, could someone please link to me a post, or share their own config files, or help me out by pointing me in the right direction?
The primary files that I edit, are .jsx files, without a .tsconfig in the directory (could this be the reason)?
Please let me know if this is not the correct platform to ask this question. Thank you.
Posting my init.vim below, in case that would help:

set runtimepath^=~/.vim runtimepath+=~/.vim/after
let &packpath = &runtimepath
source ~/.vimrc

if (has("termguicolors"))
  set termguicolors
endif

call plug#begin()
  Plug 'neovim/nvim-lspconfig'
  Plug 'nvim-lua/completion-nvim'
  Plug 'nvim-lua/popup.nvim'
  Plug 'nvim-telescope/telescope-fzy-native.nvim'
  Plug 'nvim-lua/plenary.nvim'
  Plug 'nvim-telescope/telescope.nvim'
  Plug 'kabouzeid/nvim-lspinstall'
  Plug 'sbdchd/neoformat'
  Plug 'sickill/vim-monokai'
  Plug 'morhetz/gruvbox'
  Plug 'nvim-treesitter/nvim-treesitter', {'do': ':TSUpdate'}
  Plug 'sonph/onehalf', {'rtp': 'vim/'}
  Plug 'sainnhe/everforest'
  Plug 'sainnhe/gruvbox-material'
  Plug 'junegunn/seoul256.vim'
  Plug 'simrat39/symbols-outline.nvim'
  Plug 'tpope/vim-commentary'
  Plug 'tpope/vim-surround'
  Plug 'hoob3rt/lualine.nvim'
  Plug 'kyazdani42/nvim-web-devicons'
  Plug 'ryanoasis/vim-devicons'
  Plug 'glepnir/lspsaga.nvim'
  Plug 'chrisbra/Colorizer'
call plug#end()

lua << EOF
require('telescope').setup{
  defaults = {
    vimgrep_arguments = {
      'rg',
      '--no-heading',
      '--with-filename',
      '--line-number',
      '--column',
      '--smart-case'
    },
    prompt_prefix = "> ",
    selection_caret = "> ",
    entry_prefix = "  ",
    initial_mode = "insert",
    selection_strategy = "reset",
    sorting_strategy = "descending",
    layout_strategy = "horizontal",
    layout_config = {
      horizontal = {
        mirror = false,
      },
      width = 0.75,
      preview_cutoff = 120,
      prompt_position = "bottom",
      vertical = {
        mirror = false,
      },
    },
    file_sorter =  require'telescope.sorters'.get_fuzzy_file,
    file_ignore_patterns = {},
    generic_sorter =  require'telescope.sorters'.get_generic_fuzzy_sorter,
    winblend = 0,
    border = {},
    borderchars = { '─', '│', '─', '│', '╭', '╮', '╯', '╰' },
    color_devicons = true,
    use_less = true,
    set_env = { ['COLORTERM'] = 'truecolor' }, -- default = nil,
    file_previewer = require'telescope.previewers'.vim_buffer_cat.new,
    grep_previewer = require'telescope.previewers'.vim_buffer_vimgrep.new,
    qflist_previewer = require'telescope.previewers'.vim_buffer_qflist.new,
    -- Developer configurations: Not meant for general override
    buffer_previewer_maker = require'telescope.previewers'.buffer_previewer_maker
  },
  extensions = {
    fzy_native = {
        override_generic_sorter = false,
        override_file_sorter = true,
    }
  }
}
require('telescope').load_extension('fzy_native')
EOF

nnoremap <leader>ff <cmd>lua require('telescope.builtin').find_files()<cr>
nnoremap <leader>fg <cmd>lua require('telescope.builtin').live_grep()<cr>
nnoremap <leader>fb <cmd>lua require('telescope.builtin').buffers()<cr>
nnoremap <leader>fh <cmd>lua require('telescope.builtin').help_tags()<cr>

set completeopt=menuone,noinsert,noselect
let g:completion_matching_strategy_list = ['exact', 'substring', 'fuzzy']

let g:completion_chain_complete_list = {
            \ 'default' : {
            \   'default': [
            \       {'complete_items': ['lsp', 'snippet']},
            \       {'mode': '<c-p>'},
            \       {'mode': '<c-n>'}],
            \   'comment': [],
            \   'string' : [
            \       {'complete_items': ['path']}]
            \   },
            \}

inoremap <expr> <Tab>   pumvisible() ? "\<C-n>" : "\<Tab>"
inoremap <expr> <S-Tab> pumvisible() ? "\<C-p>" : "\<S-Tab>"

lua << EOF
local on_attach = function(client, bufnr)
  local function buf_set_keymap(...) vim.api.nvim_buf_set_keymap(bufnr, ...) end
  local function buf_set_option(...) vim.api.nvim_buf_set_option(bufnr, ...) end

  --Enable completion triggered by <c-x><c-o>
  buf_set_option('omnifunc', 'v:lua.vim.lsp.omnifunc')

  -- Mappings.
  local opts = { noremap=true, silent=true }

  -- See `:help vim.lsp.*` for documentation on any of the below functions
  buf_set_keymap('n', 'gD', '<Cmd>lua vim.lsp.buf.declaration()<CR>', opts)
  buf_set_keymap('n', 'gd', '<Cmd>lua vim.lsp.buf.definition()<CR>', opts)
  -- buf_set_keymap('n', 'K', '<Cmd>lua vim.lsp.buf.hover()<CR>', opts)
  buf_set_keymap('n', 'gi', '<cmd>lua vim.lsp.buf.implementation()<CR>', opts)
  -- buf_set_keymap('n', '<C-k>', '<cmd>lua vim.lsp.buf.signature_help()<CR>', opts)
  buf_set_keymap('n', '<space>wa', '<cmd>lua vim.lsp.buf.add_workspace_folder()<CR>', opts)
  buf_set_keymap('n', '<space>wr', '<cmd>lua vim.lsp.buf.remove_workspace_folder()<CR>', opts)
  buf_set_keymap('n', '<space>wl', '<cmd>lua print(vim.inspect(vim.lsp.buf.list_workspace_folders()))<CR>', opts)
  buf_set_keymap('n', '<space>D', '<cmd>lua vim.lsp.buf.type_definition()<CR>', opts)
  -- buf_set_keymap('n', '<space>rn', '<cmd>lua vim.lsp.buf.rename()<CR>', opts)
  -- buf_set_keymap('n', '<space>ca', '<cmd>lua vim.lsp.buf.code_action()<CR>', opts)
  buf_set_keymap('n', 'gr', '<cmd>lua vim.lsp.buf.references()<CR>', opts)
  buf_set_keymap('n', '<space>e', '<cmd>lua vim.lsp.diagnostic.show_line_diagnostics()<CR>', opts)
  buf_set_keymap('n', '[d', '<cmd>lua vim.lsp.diagnostic.goto_prev()<CR>', opts)
  buf_set_keymap('n', ']d', '<cmd>lua vim.lsp.diagnostic.goto_next()<CR>', opts)
  buf_set_keymap('n', '<space>q', '<cmd>lua vim.lsp.diagnostic.set_loclist()<CR>', opts)
  buf_set_keymap("n", "<space>f", "<cmd>lua vim.lsp.buf.formatting()<CR>", opts)

  require('completion').on_attach(client)
end

local function make_config()
  local capabilities = vim.lsp.protocol.make_client_capabilities()
  capabilities.textDocument.completion.completionItem.snippetSupport = true
  return {
    -- enable snippet support
    capabilities = capabilities,
    -- map buffer local keybindings when the language server attaches
    on_attach = on_attach,
  }
end


local function setup_servers()
  require'lspinstall'.setup()
  local servers = require'lspinstall'.installed_servers()
  for _, server in pairs(servers) do
    local config = make_config()
    require'lspconfig'[server].setup(config)
  end
end

setup_servers()
-- Automatically reload after `:LspInstall <server>` so we don't have to restart neovim
require'lspinstall'.post_install_hook = function ()
  setup_servers() -- reload installed servers
  vim.cmd("bufdo e") -- this triggers the FileType autocmd that starts the server
end
EOF

set background=dark
" let g:gruvbox_contrast_dark = 'hard' 
" let g:gruvbox_bold = 1
" colorscheme gruvbox
" colorscheme onehalfdark
colorscheme gruvbox-material

let g:symbols_outline = {
    \ "highlight_hovered_item": v:true,
    \ "show_guides": v:true,
    \ "position": 'right',
    \ "auto_preview": v:true,
    \ "show_numbers": v:false,
    \ "show_relative_numbers": v:false,
    \ "show_symbol_details": v:true,
    \ "keymaps": {
        \ "close": "<Esc>",
        \ "goto_location": "<Cr>",
        \ "focus_location": "o",
        \ "hover_symbol": "<C-space>",
        \ "rename_symbol": "r",
        \ "code_actions": "a",
    \ },
    \ "lsp_blacklist": [],
\ }
nnoremap <Leader>o :SymbolsOutline<CR>

lua << EOF
require'nvim-treesitter.configs'.setup {
  ensure_installed = "maintained", -- one of "all", "maintained" (parsers with maintainers), or a list of languages
  highlight = {
    enable = true,              -- false will disable the whole extension
  },
  indent = {
    enable = true,
  },
  autopairs = {
    enable = true,
  },
  rainbow = {
    enable = true,
  },
  autotag = {
    enable = true,
  },
  context_commentstring = {
    enable = true,
  }
}
EOF

lua << EOF
require'lualine'.setup {
  options = {
    icons_enabled = true,
    theme = 'gruvbox',
    component_separators = {'', ''},
    section_separators = {'', ''},
    disabled_filetypes = {},
    options = {
      icons_enabled = 1, -- displays icons in alongside component
      padding = 1, -- adds padding to the left and right of components
      left_padding = 1, -- adds padding to the left of components
      right_padding = 1, -- adds padding to the right of components
      upper = false, -- displays components in uppercase
      lower = false, -- displays components in lowercase
    }
  },
  sections = {
    lualine_a = {'mode', { 'diff', colored = true }
    },
    lualine_b = {'branch'},
    lualine_c = {{ 'filename', file_status = true, path = 2 }},
    lualine_x = {'encoding', 'fileformat', 'filetype'},
    lualine_y = {'progress'},
    lualine_z = {{
        'diagnostics',
        sources = {'nvim_lsp'},
        -- displays diagnostics from defined severity
        sections = {'error', 'warn', 'info', 'hint'},
        -- all colors are in format #rrggbb
        -- color_error = '#E06C75', -- changes diagnostic's error foreground color
        -- color_warn = '#E5C07B', -- changes diagnostic's warn foreground color
        -- color_info = '#61AFEF', -- Changes diagnostic's info foreground color
        -- color_hint = '#56B6C2', -- Changes diagnostic's hint foreground color
        symbols = {error = 'E', warn = 'W', info = 'I', hint = 'H'}
      }}
  },
  inactive_sections = {
    lualine_a = {},
    lualine_b = {},
    lualine_c = {'filename'},
    lualine_x = {'location'},
    lualine_y = {'progress'},
    lualine_z = {}
  },
  tabline = {},
  extensions = {}
}
EOF


lua << EOF
local saga = require 'lspsaga'
-- add your config value here
-- default value
-- use_saga_diagnostic_sign = true
-- error_sign = '',
-- warn_sign = '',
-- hint_sign = '',
-- infor_sign = '',
-- dianostic_header_icon = '   ',
-- code_action_icon = ' ',
-- code_action_prompt = {
--   enable = true,
--   sign = true,
--   sign_priority = 20,
--   virtual_text = true,
-- },
-- finder_definition_icon = '  ',
-- finder_reference_icon = '  ',
-- max_preview_lines = 10, -- preview lines of lsp_finder and definition preview
-- finder_action_keys = {
--   open = 'o', vsplit = 's',split = 'i',quit = 'q',scroll_down = '<C-f>', scroll_up = '<C-b>' -- quit can be a table
-- },
-- code_action_keys = {
--   quit = 'q',exec = '<CR>'
-- },
-- rename_action_keys = {
--   quit = '<C-c>',exec = '<CR>'  -- quit can be a table
-- },
-- definition_preview_icon = '  '
-- "single" "double" "round" "plus"
-- border_style = "single"
-- rename_prompt_prefix = '➤',
-- if you don't use nvim-lspconfig you must pass your server name and
-- the related filetypes into this table
-- like server_filetype_map = {metals = {'sbt', 'scala'}}
-- server_filetype_map = {}

saga.init_lsp_saga()
EOF

nnoremap <silent>gh :Lspsaga lsp_finder<CR>
nnoremap <silent><leader>ca :Lspsaga code_action<CR>
vnoremap <silent><leader>ca :<C-U>Lspsaga range_code_action<CR>
nnoremap <silent>K :Lspsaga hover_doc<CR>
" -- scroll down hover doc or scroll in definition preview
nnoremap <silent><C-f> <cmd>lua require('lspsaga.action').smart_scroll_with_saga(1)<CR>
" -- scroll up hover doc
nnoremap <silent><C-b> <cmd>lua require('lspsaga.action').smart_scroll_with_saga(-1)<CR>
nnoremap <silent>gs :Lspsaga signature_help<CR>
nnoremap <leader>rn :Lspsaga rename<CR>

One option you’re missing is flags.debounce_text_changes, see the lspconfig readme. Other than that, make sure your root directory appropriately detects your project (:LspInfo). Also note that we cannot use tsserver directly like CoC which forks the vscode typescript extension, because tsserver does not directly implement the language server protocol. We have to use GitHub - theia-ide/typescript-language-server: TypeScript & JavaScript Language Server which adds some overhead.

Thanks, I’ll add the option and check it out! Could the autocompletion issue be resolved with this as well? Or is there another thing I can change in my config that would help? Or is that another issue altogether, and not answerable over here?
Thanks a lot anyway!

I added flags.debounce_text_changes to my config, still the issue is the same. Would you have any other ideas that might be the problem? Or perhaps it is the typescript language server that is the problem?

which snippet engine are you using?
for vsnip, you can put this in your global or local on_attach function

vim.fn["vsnip#get_complete_items"](vim.fn["bufnr"]())

So that there is no delay when autocompleting, it fetches it beforehand.
I am sure there must be similar feature for other snippet engines