Hmm.. I haven't ordered much from Nashbar, but I'll agree that they appear to be prompt with shipping.
With Performance, if you don't pay for the 2 day upgrade, they seem to ship their items whenever they feel like it. However, if you join TEAM PERFORMANCE for $20, all your shipping is upgraded to 2 day automatically. You also earn 10% back in what amounts to store credit. I've easily earned back my $20 membership fee.
Outside of the non club members shipping issues, their customer service is outstanding.
Personally, when I order online, I go with performance. There seems to always be a 20% off coupon available, you earn 'points', and as a Team performance member, you get your item in 2 days.
However, if possible I buy from the LBS.