I notice this especially in the usb flash drive, when i put my mouse over a pdf file with many pages (over 9mb in size)
edit: i can confirm this also happens in other places besides the flash drive area. When i put my mouse over a large pdf file it dolphin will hang up for around 3 to 5 seconds.
out of curiosity which version of kde and dolphin are you using? i used to see the same behavior in kde4.0 but haven’t seen it since switching to kde4.1
Im using kde 4.2.2 and dolphin 1.2.1
I wish I could help, I’ve seen this behavior in 4.1 and 4.2 when I try to open a video in my windows partition or a .mp4 file anywhere. Dolphin would become unresponsive for about 15 seconds then it would work normally. I haven’t had the problem in 4.3 yet (knock on wood).
Here’s the bug report https://bugs.kde.org/show_bug.cgi?id=163050