Your ping goes to ~900 after you press ESC in a match?
and it takes from 2 to 3 minutes for it to go down?
THE SOLUTION
The problem is the loading of News in the main menu, the workaround is to block it:
Go to your hosts file located here: C:\Windows\System32\drivers\etc
Open “hosts” with notepad
Enter the following line at the end:
127.0.0.1 blog.counter-strike.net