Macs have never been very fast, nor very expandable.
And Apple never claimed they were - they were focusing on other things:
First, their selling point was "100% pure GUI", while in the PC world a GUI was optional, rare, and not very useful.
Later on, when GUI became ubiquitous on PCs as well, Apple made various other claims: no compatibility problems, as all components came from one vendor, quieter, more stylish...

And, despite the not-so-great performance, they were pretty successful even among professional users, mostly DTP and graphics, see eg. Quark Xpress and Adobe Photoshop.

Today, there's much rumors about professionals running away from Macs.
Does it mean that the current lack of performance is worse than ever before, or are those rumors exaggerated?