There's very little resistance between slide and frame when I field strip my VP9. It's quite smooth actually. Then again, I've put 4000+ rounds on my VP9 and have cleaned and lubed it about 9 times.
Is this the first time you have field stripped your gun? Are you disassembling and assembling your gun correctly? Have you lubricated your VP9 per the owner's manual? You need to provide more info. Too many variables here.