I'm extremely slow at the cross. I do F2L in about 20 seconds, OLL in 5 and PLL in five. The cross takes me an average of 10 seconds. This is just slowing me down too much.
Help?

Realize that you don't have to actually solve the cross until the very last move, when you can align the layer.
Hold your cube yellow on top, orange in front. Preform D2 B2 R' L' U2 F. Say you are solving the cross on white. Instead of matching the cross edges to their respective centers BEFORE swinging them into the cross layer, sometimes it would be much better to, for example, match the cross edges with the OPPOSITE centers, and then do a 180 degree turn of the cross layer at the end to align everything. So, in this example, I'd solve the red cross edge with the orange center with an F', then solve the green cross edge with the blue center with an R, and so on.
The first thing I do in my inspection is decide whether I will be placing cross edges correctly, or oppositely.
Being able to do the cross by solving the edges WITH RESPECT TO EACHOTHER will make solving the cross much faster
Also, watch some of badmephisto's (and others') videos on the cross.

If you're willing to set aside a little bit of time, this would be the best video to watch. It teaches you about the concepts of good and bad edges, and gives example solves to follow along with. Speaking of example solves, search some out so you can develop your own style- even an experienced speedcuber still has something to learn by watching others.

Another suggestion for people who want to get faster at the cross is to scramble, inspect, then do it with your eyes closed. This trains you to plan the entire cross ahead of time so your brain can focus on the first F2L Pair or whatever you do after the cross.