Visual Studio incredibly slow when renaming files

Question

I have a medium-sized solution with 99 projects that has recently started behaving weirdly:

1) If I try to rename a file through the solution explorer, VS will seem

Answer 1

Building on @Daniel Barbalace's answer, my issue indeed had to do with TFS, but I could not switch to server workspaces. What I ended up doing was removing the mappings to any branches or projects that I am not working on at the moment. There is no magic number but once I seemed to get under 50,000 files (globally for the TFS folder) renaming suddenly went down from 2+ minutes to 3-5 seconds.