Inserting a code block delays real-time previews

Hello!!
Markdown-preview works pretty well in my environment. But adding a code block delays the real-time preview. Everything else works fine, but when I move the cursor in the code, the display being moved to Chrome is delayed. Do you need any settings?

[issue]

```
code block
```

[Environment]
Ubuntu 20

.config
│
nvim
├── colors
│   └── material-monokai.vim
├── dein.toml
├── dein_lazy.toml
├── functions.rc.vim
├── init.vim
├── keymap.rc.vim
├── options.rc.vim
├── plugins
└── snippets
├── c.snip
└── markdown.snip

dein.toml
.
.
.
[[plugins]]
repo = 'iamcco/markdown-preview.nvim'
on_ft = ['markdown', 'pandoc.mardown', 'rmd']
build = 'sh -c "cd app & yarn install"'
hook_add = '''
let g:mkdp_refresh_slow = 1
let g:mkdp_command_for_global = 1
let g:mkdp_open_to_the_world = 1
let g:mkdp_echo_preview_url = 1
'''