This comes from chdir, so it’s not really creating/reading a file but switching the current working dir for the Renoise process.
We always do set the current working dir to the tool’s bundle directly before calling into a scripting tool, to make relative imports work. If we wouldn’t, lua requires with relative paths would fail.
I don’t think that this is causing the Slow plugin loading issue, as the original author also has the problem when all tools are disabled.