Does Roehsoft RAM Expander need to be running?

You should be able to close the application and possibly uninstall it afterwards, the swap file is based on making a portion of your SD Card a swap partition, like virtual memory on a PC, ReadyBoost USB or swap partitions for linux, the system will now use it as virtual ram and therefore shouldn't require the application anymore.

It's good to remember that when you increase your memory availability, this often requires an extremely quick storage device otherwise it'll just slow your device down if anything.

Think of the average RW speed of RAM, around 800mbs and then the RW speed of your SD card, around 30mbs at max, you'd be potentially forcing your system to use a 30mbs virtual ram over a 800mbs physical ram.. Let's say you had to calculate just one 800mb task, if the task got placed on the virtual ram before execution it would take around 27 seconds to collect the information for execution, however if it got placed on the physical ram it'd take just 1 second.

It is good for some things that don't require high speeds, like switching between multiple applications etc..

In my day's of trying to upgrade Android without buying a new device, i found that Pimp My Rom (PMR) was one of the best applications for speeding up my device. PMR requires the application to be installed but not running. Pimp My Rom version 1.0

It's still in the beta stage but it's free.

XDA Page for Pimp My Rom

Always make a backup before doing any system changes, especially using a beta stage app like this because some features might be device dependent, at not supported on others.

I found Entropy Generation, Build.prop performance tweaks and internet (build.prop) tweaks make a noticeable difference to performance of the entire device experience, if i get rid of the bloatware for more system memory, that sometimes increased the speed even more.