Synchronized Files Comparison

I recently did a php project on my server, but when I used the CTRL + U sync option, I checked an option where I asked to sync the remote folder with the local one, and now it compares all 10,000 files in the folder. How do I stop him from buying the files in the synced folder anymore?

he spends a lot of time comparing, not synchronizing

I'm sorry, I do not understand what you ask for.
If you do not want WinSCP to do full synchronization before starting to watch for changes, do not check that option.
Make sure you read documentation, if you are not sure, what the option(s) mean.
https://winscp.net/eng/docs/ui_keepuptodate