DS220J slow after camera install

[Enquiries]

I purchased my first NAS, a Synology DS220J about 18 months ago, mostly for photo and Desktop backup. I had a lot of photos and so it was slow to index them all and still a little slow, but livable to use when editing them.
Recently I installed two ip cameras and the performance/response has become almost unusable both for surveillance station and for photos.
The NAS is not doing anything else, so why so slow with only two cameras. The memory is at 60% and the CPU is less than 15%.

Thanks.

[ed]

CCTV cameras keep those drives bussy. Also, that RAM is really inefficient to run something more than simple file storage and backups. Consider 1-2GB RAM-based models. Having a separate NAS or even separate RAID for CCTV improve things.