If cost isn't an issue.....what is the performance issue? I've been using zeros for about 10 years now. I've tried Shimano and Time pedals during that 10 year period, and always end up back at speedplay. The float is awesome, and they are deadly easy to get clipped into.

Just to note, shimano works better for me but they come with their own pro/cons too:

Speedplay problems off the top of my head.:
-Float adjust screws "self adjust" and float drifts over time.
-debris/dirt collect in cleats and can make it difficult to clip in.
-Clip out force changes with cleat wear.
-Phillips head screws securing the cleat wear and fill with dirt, can be hard to get them unscrewed during cleat change.
-Pedals require relube of bearings regular basis.
-People don't really need all the pedal float they think they do, so the float benefit of speedplay isn't a big advantage.
-Large amounts of lateral rock with pedal body/cleat wear.
-If you travel/rent bikes you will need to bring your pedals also. Shops almost always can fit shimano compatable pedals if you have shimano cleats.

Overall cost of ownership much higher than shimano.