We know PS3's slowness has got you down, and we are really sorry! Trust us when we say we haven't been ignoring you; We have been working hard on PS3 and PS4 to improve things as much as possible.
Here is the what we know, and we want to share with you,
PlayStation 3 has very little memory and makes even less of it available to us. When the app runs out of memory it starts paging to disk (It means the data from faster RAM is being moved to much slower Hard Disk. You can literally see the PS doing this because there is little orange light on the front of the device that starts blinking or just lights up, that's the HDD activity indicator) this causes the app to become extremely unresponsive and freeze at times.
What are we going to do about it?
We are preparing a release that cuts down on the eye-candy and limits the amount of data that gets processed by the app, This should be released fairly soon and should help improve the situation. (Done. See update 1 below)
We are also preparing a platform update for PS3, this will bring PS3 to use the latest SDK that gives us a bit more RAM and also should be more efficient with the RAM we already have, This will take a bit longer since it needs to get tested on our side and then submitted to Sony for approval.
What does this mean for PS3 long term:
We have no plans to abandon or drop support for PS3. _However _ I think it's important to set the correct expectation. The PS3 was released ~10 years ago (1 year before the original iPhone!) and has proven very challenging to support. We'll do our best to support the device to the best of its capabilities while focusing on maintaining a stable experience. New Plex features will be introduced less frequently than on the PS4 and other modern devices.
Update 1 (June 2nd, 2016):
We just deployed the cut-down version of the PS3 app (2.6.5), restarting the app should give you the newer version.
Keep in mind even though this should improve the situation it's not a fix, we have more changes coming, especially in the platform update which should hopefully resolve this issue,
Few things that we have changed that you might be interested in:
Companion (being able to control the APP using your mobile phone) is now disabled by default for PS3 since it was too resource consuming, if you use it you can still enable it in Settings > Main > Companion Player
Make sure network logging is disabled in Settings > Privacy > Log to Media Server unless you are trying to report an issue and disable it as long as you have the logs you need