Originally Posted by feline fanatic

Try starting your seam from the center of your pinwheel block. Then flip it over and do the other side. This allows you to furl the seam in the center as well.

Edited to add you can also try this method from Green fairy but I'm not sure it will help with your machine bogging down at the center. It will help avoid the bulk in the finished unit though.
http://www.greenfairyquiltsblog.com/...lat-seams.html