Does deleting temporary files really speed up your computer? (Windows)

Question

You've most certainly read it on the internet, and you may have even heard other supposedly computer-savvy people suggest that deleting temporary files speeds up your (Windows) computer.

But how does that actually work? Drawing on my limited theoretical knowledge of file systems and disk drives, I cannot understand how deleting temporary files should improve file system performance unless the disk is nearly full. How can a temporary file that just sits there impair performance? Can somebody offer a technical explanation of why deleting temporary files (and cookies, and prefetch files) should or shouldn't have an effect on performance?

Edit: It appears that Microsoft thinks so.

Answer 1

I can certainly vouch for the speedup associated with having a huge number of files in your temp folder. I've had my current laptop for 2-3 yrs and never deleted temp files... then one day I installed AVG PC-Tuneup and inadvertently deleted my temp files (the UI sucks). Wham! Actual, percievable speedup.

I can think of a few reasons for why:

1) NTFS has to make 8.3 filesnames for every file (unless you tweak it via fsutil). Its gets progressively harder once your folder has a large number of files. Also applications that make the temp files, have to search for a unique name. I had a pokey old 4200 rpm drive, so each seek was very expensive, and lots of seeks were needed because (see point2)

2) Size of the MFT. The Master File Table can become many hundreds of MB in size and won't be cached as often (or atleast more of it will pbe paged out all the time). ntfsinfo from Sys Interals will give you the deets...

3) Each time the temp folder is enumerated - there's a lot more work to be done - esp. if you have a virus scanner that checks all the files in a folder, each time the folder is enumerated! I'd also been very aggresive with Windows Search indexing. Excluding the temp folder from the index, helped speed-up my computer too...

Answer 2

While I think the performance increase is fairly small, I see two reasons why it could make a difference:

• It decreases filesystem fragmentation. Edit: or quite the inverse? see comments
• It could speed up temporary files scanning and creation for some programs. Some programs create consecutively numbered files (file001.tmp, file002.tmp, ...) in the temp folder, but in order to find out the latest number some simple/stupid approach might be to try each number in order, until a filename is not yet taken. I assume this process takes some time (8 msec for a disk seek according this perhaps outdated reference) if you've accumulated a few years of temporary files.

Answer 3

I agree with Grynn, but have another thing to consider. With the fact that the more data stored on HDD (not mention SSD here) the slower the read/write becomes, it's clear that PC with hundreds GB of data should be slower than one has a fewer data. Also, if the PC has AV software, it will usually scan for data on the disk, each time of boot or some scheduled time. Windows has a feature named "Index" to make the file searching gets quickly, it might affect the performance too if users has lots of temporary files too (though I think Index will ignore the temp folder). But I believe that the reason is related to the physical properties of HDD more than OS and software.

Answer 4

Yes, regularly deleting temporary files does speed up your computer, but the "amount of speed up" depends on memory, processor and how often is this folder used.

On my old computer I did this every week, on my current one - once a month or two. (Yes, I have an antivirus software.)

More important is that the trash bin should be empty or almost empty.