In current Windows 10 versions, Windows Defender can be rather aggressive in scanning files while they are being written. You can observe this frequently using Task Manager with “More Details” and sorting Processes by CPU or Disk load.
On some systems, this can slow down writing sim caches quite a bit, which in turn makes the sim computation sit idle until the caches have been flushed. Since you can safely assume that Defender won’t find anything malicious in TFD’s sim caches, it’s a good idea to disable scanning of the cache folder(s) entirely.
It is particularly useful for sim caches like those written by TFD, but this is certainly true for any folder that gets written to frequently enough to be performance sensitive.
The folder exclusions can be added in
Settings / “Virus & thread protection settings” / Exclusions / “Add or remove exclusions”.
You can find it like this:
Click on “Manage settings”.
Scroll down to Exclusions and click Add or remove exclusions.
Then use “Add an exclusion” to add all folders that you might use for sim caches.