Since the upgrade to 1.1.0 and 1.1.1, Piwik seems far slower than 1.0.0.
Especially “live” (but other widgets too). Just an impression ?
Thats recorded in the forums in some places already.
Especially the live plugin is causing these issues currently and I think there was a bug with pdf reports too.
If you disable these there should be around the same performance as before.