'alt+tab' menu has a 1.5 sec of latency

[Luca Chiodini]

The issue has never been, it comes with Unity 5.2

- Press 'alt'+'tab'

Result:
- Wait about 1,5 sec / 2 sec
- The menu appears

What should happen (happened before unity 5.2)
- the menu appears suddenly

I'm here if some logs are needed
The PC has a intel t4400 processor and 4 GB of RAM, so the computer speedy isn't the issue.

[Nekhelesh Ramananthan (nik90)]

Thank you for reporting the bug. I understand there is a very small delay before the alt-tab appears but not as much as 1.5 secs. Could you provide a video screencast? Probably the problem is only on your end.

[Jan Claeys (janc)]

Not tested with Unity 5.2, but this also happens with older versions (e.g. those included in Ubuntu 11.10) when you keep your system running for some time. The reason is quite simple: memory leaks causing parts of compiz/unity to get paged out to the swap, then when you press Alt-Tab, those memory pages have to be paged in again...

[Jan Claeys (janc)]

So does the 1.5 sec delay happen always, or only after some time?

[Jan Claeys (janc)]

Or even otherwise, is any process using abnormal amounts of memory?

[Luca Chiodini (l-chiodini)]

@Jan Yes, the problem happens after the system has a high uptime (minimum about one hour).
I've seen (by the command 'top') that Xorg process, during I press Alt+Tab, uses about the 40% of CPU.
I don't think it's really normal.

[Launchpad Janitor (janitor)]

[Expired for unity because there has been no activity for 60 days.]