If paging is a problem, it could be the dynamic nature of the pagefile on Windows.
On Windows, your pagefile does not have a fixed size. It grows and shrinks. This costs extra time. Especially if you have little space left on your disk. Or when the disk is heavily fragmented.
You could set a fixed size for your pagefile. Open the system control-panel. Advanced tab. Performance. Click Settings button. Advanced tab. Virtual Memory. Click Change.
Set your pagefile on one disk. Select custom size. Put the initial size and the maximum size to the same value. If you have 8GB ram in your system, then 4GB for the pagefile should be enough (that's 4096 MB). Set the values to 0 on the disks you are not using for the pagefile.
Maybe it helps. Maybe it doesn't. It's only a few minutes to configure this. If it doesn't help, it won't hurt either. Worth a try.
====
If you have less than 8GB of physical ram, you might have a problem. That you can't fix.
If you have more than 8GB of physical ram, there might be a memory leak. I think it's unlikely the leak is in GTAV itself. Or else there would be more complaining. Maybe in a mod ?
When you have memory problems, the default thing to do is to run the game with no other applications running. No browser open. No stuff running in the background. Etc.