Automatic defragging is part of windows since some time, so I wonder what any third party tool would do differently and why they are needed nowdays at all.
I expect these tools to use the same API microsoft provides, so theoretically, there cannot be a huge difference in performance between one defrag and another.
These days defragging is more than just putting all clusters of a file together in sequence. Many programs provide optimization in the form of moving the most used files to the front of the disk to minimize head movement. They also do other grouping to speed up access. These features are not provided by MS. It is possible that some defrag software is better than other programs.
Also, it is possible that the OP had disabled the MS defrag (especially if he is using 3rd party products) so his disk was not being defragged by MS.
The builtin windows 7 defragging scored quite good, it reached 4th place in a comparison between 16 3rd party tools.
The comparison confirms my expectations. There are a few situations, where some tools squeeze out some seconds when booting windows or loading huge games and applications, but the general speed-up against the win7-defrag is barely noticeable.
Very surprising is, that many of the other tools actually reduce the performance, I didn't expect that.
Conclusion for me: Unless you tested and know that your particular defragger beats the builtin defragging at the task you care about (loading windows e.g.), better not use it. If you're lucky you might gain around 10 percent here or there, but the chances are quite high to end up with less performance than before. Taking into account the time it takes to setup benchmarking and tests, it does not seem to be worth the hassle for me, but this is just my thinking and I won't deny, that there might be specific scenarios which benefit from doing all this.
I tend to spread pagefiles across disks in a system. Does it increase performance?
I don't know - theoretically it should, but I never tested - maybe just another old-fashioned habbit! o)
If they are separate physical disks, then yes. It's meant to be faster than having page file on one disk. But if you have only one disk or split page file across more than one partition within a disk, you will probably end up with lower performance.
Reasons for lower performance:
there will be more drive's head movement
in standard disks (vs SSD ones) files located at the beginning of a disk have better performance (up to or even more than 2x faster when compared to end of a disk).