Many users reporting that language check with VSCode is very slow. I can confirm it on RPI3b and on Rock64.
I am wondering is the problem is not with LSP implementation only, but with how it is used in VSC.
I can see that for every character typed the LSP check is issued. This is queued for all characters entered.
Better it would be to do an delta check periodically e.g. every 15-30s.
Can somebody have a look of possibilities at VSCode to do so.