IMHO It depends on why your slow. But a good coach will figure that out for you and help you straighten it out.
If you are a do-it-yourself type there are many web sites that can show what fast should look like. Google search will get you to them.
We had 2 kids that were well below average on the basepaths. In both cases the issue was stride length. They took very short steps. So we measured their strides, folded mainila envelopes into 6"x12" markers at their respective stride lengths, layed them out down a 25 yard running path and let them run over them. Gradually we increased the distance between each marker an inch or two until the distance was more proportionate to their height and the kids ended up with respectable speed. This only took a couple of weeks
Another quick fix is to find a hill and run down it. Not too steep , you don't want to train your body to try and stop itself. But you can get your body used to speed and it will want to re-find that speed when you run.
Hope that's helpful