Default Setting for fetching_timeout

[DoeringChristian]

Hi,

I have been using neovim for some time and I only had one mayor problem, that was the input lag I perceived when running an LSP and typing text.
After some testing I could track the issue down to nvim-cmp.
Then I found the setting performance.fetching_timeout and its default of 500ms, which can be noticeable.
If I understand it correctly this setting sets the timeout, cmp waits for a response from the LSP before sorting and displaying the results.
A smaller value therefore has mostly an impact on the sorting quality.
For me a setting of 100ms soved the problem entirely.
As I have noticed multiple discussions on the topic of lag (#1282, #148 etc.)
I would propose to add a troubleshooting item that explains this for users who experience lag.

Thanks for the great plugin.