What you are experiencing isn't the game running slow, that's how the lag system in CF works. Certain things are one round of lag, others are two, others are three or four, etc. Additionally, some people can do things to you which will slow you down, like bashing, tripping, pincering, certain assassin kicks, etc.

So, lets say you're a mage and you blind a mob in combat. For one whole round after, (one snippet of combat text) you won't be able to do anything else. Lets say someone on the other hand trips you, you will not be able to do anything for two full combat rounds and after which, you'll be able to get in exactly one command before they can trip you again, assuming they don't have cheapshot.

The newbie guide explains this a bit better than I can, you can get it from the Help section of this website.