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I'm experiencing mouse/menu latency and wondering if this is a "normal" level or if there a way to get the guest linux UIs to respond to the mouse with lower latency ...

When I use the mouse in the VM the mouse cursor moves smoothly but there is a significant lag in the application or window manager responses: like, a short pause from mouse-click until window-selected; or, after I click open the File menu ins an app and then move the mouse cursor downwards, there isn't any menu-item highlighting until I stop and wait for a second; or, if I click-open the File menu, then slide the mouse sideways along the menu bar, the Edit etc menus don't drop down as I go along, until I stop (or unless I move quite deliberately).

When the menus *do* drop, or the highlight moves, the repaint speed is fine. And, the CPU/disk performance seem fine and reasonable. But the UI mouse-latency is *way* slower than, for example, an on-the-metal installation of Fedora 20 running Gnome 3 on my ancient Lenovo laptop with a dual-core T7700/Nividia NVS140M.

So the first question is, is this "normal" or are other people getting responsive UI?

Then, if it's not normal, what might be the issue?

I've tried different VMs and various apps, window managers, etc. It seems to be the same lag in all of them, and the same whether I'm in windowed, fullscreen, or even seamless modes (though, I've done very little testing in fullscreen and seamless, just a quick check).

Host is Win 7 64 bit, i7, 16GB RAM/SSD, VirtualBox 4.3.6, with Guest Additions installed. VBox.log from most recent test on the cleanest install (Fedora 20) is attached.

Different VMs:
* Fedora 19, 3.12.8-200.fc19.x86_64 (tried Gnome, LXDE, OpenBox)
* Fedora 20 clean install, updated (Gnome, 2CPU, 1.5GB; also tried kernel "divider=10" parameter here, which seemed to make the latency worse)
* Ubuntu 13.10 (Unity)

Options I've played with: tried 3D enabled and not; tried taking CPU count for VM up to 5, down to 2; tried memory from 1.5GB to 5 GB, tried Video RAM 48MB and 128MB. Tried both "chipsets", and tried both PS/2 Mouse and USB Pointing device. I/O APIC is enabled, as is PAE/NX, and VT-x and Nested Paging.

I don't see any mouse lag with my VMs. You might want to check what CPU or I/O hogs are running (host or guest). It might be worth trying it with nCPUs set to 1 as well (don't assume that more CPUs == more performance).

mpack wrote:I don't see any mouse lag with my VMs. You might want to check what CPU or I/O hogs are running (host or guest). It might be worth trying it with nCPUs set to 1 as well (don't assume that more CPUs == more performance).

Thanks, I'll try single-CPU. When you say you don't see a mouse lag, do you mean the mouse cursor itself, or the menu response to mouse positions? My mouse cursormoves smoothly, it's just that the applications aren't quickly updating their belief about where the mouse is (when I *click* the mouse they react immediately, with a good-speed repaint as needed).

I have checked for CPU and memory hogs, and I'm not seeing anything - Windows (host) is snappy with low CPU usage, and lots of spare memory, and the Fedora 20 test was with a fresh install, nothing added except what was required to install Guest Additions. But, I'll keep looking!

wayne-o wrote:When you say you don't see a mouse lag, do you mean the mouse cursor itself, or the menu response to mouse positions?

I have not noticed a problem with either, but I don't run Fedora.

Are you sure you installed the guest additions? [Edit: never mind, I checked the log again - you did. It would be a good idea to unmount the GAs CD now though].