Springs get a bit more ticky if you need special end configurations, like compressed last coil, flat ground ends, etc. however you can do it with a couple of extra features, though it is a pain. If you use LOTS of the springs in an assembly, it is useful to have two configuration in each spring. Helix is a SLOW entity and if you have a simple cylinder/tube config. to represent them for most of the time and switch configs to the pretty version only when you need it, life will be much faster. A very dramatic demonstration of this was given at the first SW World.
For screws, please if you are not already doing so, do yourself a favor and make a simple revolve whenever possible. Only use a true helical thread when you absolutely have to.
3/4 of all the Spam produced goes to Hawaii - shame that's not true of SPAM also.......