Slowness and other weird behavior on a Windows guest

[mauricev]

This is a followup to the bug reporthttps://www.virtualbox.org/ticket/16896.

Briefly, we use a Windows program called Plexon to analyze acquired data on a Windows guest running on a OS X host. One of the tasks involves dragging the mouse around to select some data. On a specific iMac(identifier 15,1), this used to work fine in older builds of VirtualBox, but in this 5.1 release, the behavior changed. There are a few different problems. On some builds, the cursor lags behind the mouse causing dragging the mouse around to become somewhat non-responsive. In a few builds, the control key doesn't get passed to the program. In other builds, regardless of the mouse's responsiveness, the dragging is independently so slow, it's practically impossible to drag at all.

Here's a rundown of the behavior on this iMac:

5.0.38, mouse dragging works, control key works, no cursor lag.

5.0.40, not tested because the installer is not at http://download.virtualbox.org/virtualb ... 33-OSX.dmg.

5.1.0, not tested because the extension pack wouldn't install.

5.1.2, VirtualBox doesn't send the control key being pressed to the program.

5.1.4, same behavior as 5.1.2.

5.1.6, VirtualBox causes the cursor to lag with the actual mouse, resulting in uneven dragging performance.

5.1.20, VirtualBox somehow intercepts control-dragging and slows it down so much that it's practically impossible to drag.

5.1.24, same behavior as 5.1.20.

Interestingly, on a Mac Pro with 5.1.20, mouse dragging works with no cursor lag, control key works.

Vbox logs are in the attachment.