If your system mouse cursor is acting sluggish, that generally indicates something is eating up your CPU resources. A common problem is windows update running in the background and unable to complete its update due to corrupted files. Fixing this is beyond the scope of our support, but if you check your task manager and notice that one instance of svchost.exe is pegged out at 13%, 50% or 100% (depending on your # of cores) then this is likely the case.
The standalone client uses very little resources, and should run smoothly on even rather old PCs - assuming your PC isn't suffering from issues of its own.
If you're talking about a delay in response after clicking objects, that indicates a latency issue, but it's difficult to tell what kind of mouse issue you're experiencing.
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Computing the probability that at least one of the following events will occur:
P(a or b ... or z) = 1 - P(!a and !b ... and !z)
Probability
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