If you are having some occasional slow speeds, and you have multiple switches in the remote switch cabinets, try adding another cat5 cable. Then, use a cat 5 to each switch from the main cabinet to the remote switches. If more than two remote switches, you still doubled the backbone between switch cabinets, and did not spend the higher dollar on fiber. That should double your available backbone and lessen congestion.
You can now set up the one remote cabinet as if it was two, since you have two feeds to the main now. I am sure you can handle how to use the second feed cable to the main cabinet. I recomend having two feeds to the main from all remote cabinets anyway, redundancy is a good thing and a second cable in the same run is not much more money. If speed is critical, add as many twisted pair feeds between cabinets as you feel is cost effective over fiber, and your switches can utilise. You do not have to link all your remote switches directly to each other at the remote cabinet. You may not want the hassle of changing that if it is already set up that way, your call.
You do not always get what you pay for, but you never get what you do not pay for.
