the 530 is a much lower end product than the 565 and is of a previous generation of models.
Each major version of frimware has more features than the last, and as such is more 'heavyweight'
3.1.5u4 is a good version of firmware....very stable.
as is 2.1.6
the reason the 530 never saw 3.1.6 is due to lack of storage space on the device...again a reflection of a product built to a price.
trying other versions of 3.x will not result in an acceptable solution if you find 3.1.5u4 not good.
so all I can offer other than saying the 530 is a low end product, is to try 2.1.6, which 'should' be a bit quicker....but perhaps not by much at all.
And yes, you would loose your settings. Take backups, so that if you want to go back to v3 if you decide to.