Wanting to upgrade my NAS for Plex use

[Enquiries]

I currently have a Synology DS220J which doesn't support 1080p on Plex. It can also struggle if I'm downloading files to it while trying to watch Plex at the same time.
I was thinking of upgrading to a DS220+ but they are around $500 AUD on Amazon and I'm uncertain if I can simply swap my drives straight over.
I'd love some advice on whether there is anything I can do to improve my 220J's performance or whether I should consider another NAS.
Thanks in advance.

[ed]

Yes 512MB memory is the problem. Even ds223 would do better.
But DS220+ would be the best choice. It has Celeron CPU and upgradable RAM.