Hi.

Can't speak for all payware but........ my $0.02 worth on the subject......

Most payware planes are PACKED with details and features that make them WORTH the price.  The authors are competing with freeware planes.... and they have to offer stuff that makes them worth paying for.  So the "gut response" to this issue is to offer highly detailed visual models and elaborate flight systems....and sometimes animations and such.

All this "candy" comes at a price......... computer performance hits.  Some payware heavy jets will kill even the highest end machines.

If you have a lower end hardware setup....... look for "framerate freindly" planes.

best,

...................john