I have made a small change in some code but TortoiseGit shows it as modified (red exclamation sign) although I have committed, pulled, pushed, but it stays. What should I do her
Apart from what @Andy mentioned, you can make the overlays work faster by limiting the folders that it has to monitor.
Right click-> TortoiseGit -> Settings -> Icon Overlays
Here enter include and exclude paths. I usually explicitly point to the my repos / working copies: