What could be the problem with poor performance?

Question

Iron

The computer's performance began to drop significantly.

I5-7600k
mother MSI H110M Pro-vdl(MS-7A79)
8gb RAM

The specific problem is the extremely low download speed in DotA, although it is not demanding at all.
I personally sin on the RAM (it needs to be updated anyway), but I would like to make sure

Answer 1

1) Measure the speed of the Internet - maybe the provider cut a rat, it happens
2) Which disk HDD / SSD / M2, in any case, run the test with the same Victoria, most likely that there will be something "interesting" with the disk
3) You can always look at task manager → performance of what is loaded at boot time (probably the disk will be 100%)

Answer 2

The computer's performance began to drop significantly.

Well, if the computer used to work faster, what does the RAM have to do with it? Clean everything from dust, reinstall Windows. These are free actions, if they do not bring success - then already dig further.