Mavericks vs Yosemite open/save dialog

Mavericks vs Yosemite. Fresh install with latest updates. Yosemite has a performance bug on open/save dialogs MacBook Air 13" Mid-2011 1,7 GHz Intel Core i5 4 Go 1333 MHz DDR3 Intel HD Graphics 3000 Mavericks 10.9.5 Yosemite 10.10.2