Notching deck boards? I am making a deck with timbertech redwood composite decking. I...

I am making a deck with timbertech redwood composite decking. I tried to cut notch in the decking for my railing posts but i run into issues. I use a jigsaw beside the standard wood cutting blade it came beside. The saw is very hard to move along the deck (I encounter a lot of resistance) so the cuts take a particularly long time (10 minutes for one notch) and an awful lot of pushing the saw. The blade also loosens up frequently. I think the blade has too masses teeth per inch. What type of blade should I get? If you have experience, what would you suggest for notch composite decking?
Hot hose down Boiler problems, my boiler lights...
Answers:    Use a carbide tipped circular saw, make the cuts (do not walk past the corners) then cut the corners out near the jig saw, using a blade made for the composite decking.