I've got a pretty classic setup nowadays, with a smallish SSD as my C: drive where I've put my OS and programs, such as OpenStudio.

And I have a D: drive which is a regular drive but bigger, where I usually end up putting my project files because it can get big.

Since there's a lot of read/write operations going on especially when you're writing tons of output variables on a detailed timestep to the SQL file, there's likely a pretty good improvement in runtime when using the SSD.

I've noticed on opening result files from the OS App that OpenStudio seems to use the C:\Users\...\AppData\Local\Temp folder.

My question is then: is OpenStudio actually writing everything to my C drive and only at the end moving that back to my project folder?

In which case there's no point putting my project file on my SSD so I'm good to go!