Ian,
Two weeks ago I was in much the same situation as you. I began developing an app and naturally began to use filters as they seemed to be the VFP answer to 'set key to'. Everything worked fine until I tested a small prototype over a network- it was awful. I began to question whether VFP was going to work for me. Before making a bad decision, I changed some code to use local views and the speed was back. I saw somewhere on this forum where a project manager told all the programmers, if you use a filter you lose a finger. It's not that bad but close.