Windows – Does Windows use the fastest drive for the page file

Your suspicions are correct: Putting 2 page files on two different partitions on the same physical drive decreases performance because of the additional large seeks involved.

I'm not sure if Windows will let you put a page file on a USB drive, but USB 2.0 would be far too slow.

One page file per physical drive is best for performance, and Windows Vista and newer do this automatically by default, and 2000 and XP can be configured for it.

All this said, I'd you're doing enough swapping that you're worried about these kind of performance effects, then more RAM is going to be a much, much better remedy than even using a high end SSD for page file storage.

First, you have a fundamental confusion about what virtual memory is. Virtual memory is something that looks like memory. It is not the same thing as a paging or swap file. (People got this confused because adjusting the paging file is the only virtual memory setting available in the standard Windows GUI, so people started thinking they were the same thing. They are not.)

Second, "paged memory" is memory that is part of the paged pool. You want as much of your memory to be paged as possible because paged memory can be managed flexibly. Only very few things need to be non-paged.

The non-paged pool contains only memory that cannot be paged because it must remain locked in physical memory. Only data that might be needed in a context in which paging is not possible counts towards the non-paged pool. (For example, the buffers used to communicate with the hard drive controller obviously cannot be paged!) Less confusing terms would be "pageable" and "non-pageable".

Second: The vast majority of your memory is used. The only memory that's not being used is memory that's free. The usage percentage is the percentage of memory used for essential purposes. It's really only helpful to help you measure whether you might need more memory or whether memory demand is unusual. It's saying you don't need more memory and Windows doesn't need most of the memory you have, but it's using it to improve performance.

That's how it should be.

There are only two rational reasons to move your page file from an SSD to a hard drive. One would be if you need the space on your SSD. The other would be if you have an older SSD with very limited write lifetime. There's really no reason not to keep a page file on a modern SSD if you have the space. That way, if you do encounter unusually high memory demand, performance won't drop as much as it would if it had to write to a hard drive.