why use "in" here

[fedora]

Could someone here explains a little bit why it is "in", not "of" in the following sentence?

Most users report a significant decrease in download speeds

When should I use "in"?

Thanks!

[2006]

Could someone here explains a little bit why it is "in", not "of" in the following sentence?

Most users report a significant decrease in download speeds

When should I use "in"?

Thanks!

I think you mean 'download speed'. "download speeds" would mean you are talking about different available speeds: normal, fast, faster, fastest, etc.

This is a little complicated and you could use "of" in that sentence, but we tend to use "in" when talking about changes in speed.