Significant performance regression in 4.9.x / 4.10.x compared to 4.8.11.0 + Season/Specials display bug

[leshkraven 3]

After updating from 4.8.11.0 to 4.9.x and later 4.10.x, I noticed significant UI lag, artwork taking 30-40 seconds to load, sometimes even longer, shows slow to display, and general sluggishness throughout the interface. Rolling back to 4.8.11.0 immediately resolved the issue. I tested 4.9.5.0 today and the same lag is present. 4.8.11.0 runs perfectly on the same hardware with the same library.

It appears something in the image processing or metadata pipeline changed significantly from 4.9 onwards that introduces overhead on larger libraries.

Season/Specials display bug:
On shows that contain only one season folder and a Specials folder, Emby is incorrectly treating them as single-season shows and flattening all episodes into one view instead of displaying separate season folders. This issue is also present on 4.8.11.0.

The "display episodes within seasons for single season shows" setting appears to be ignoring the Specials folder when counting seasons. Even changing folder names to Season 0, with episodes correctly named S00E01 etc., does not fix the behaviour.

The only shows that display season folders correctly are those with more than one regular season — for example a show with Specials, Season 1, and Season 2 displays all three folders as expected. A show with only Specials and Season 1 gets flattened.

To put the performance regression into perspective the lag on 4.9.x is horrendous, a complete opposite experience to 4.8. Even while writing this post, I opened a show on 4.9.5.0 and after over 3 minutes the episodes still had not loaded on screen. This is on hardware that runs 4.8.11.0 without any issues whatsoever. Something has gone seriously wrong with performance between these versions. The uploaded image that shows partially loaded shows sat like that for over 8mins, I had to back out and open again which seemed to make it load fully but still took over 20secs.

It is also worth noting that when accessing Emby directly via the linux server URL locally, it does appear to load faster. This suggests the lag is amplified over remote connections, likely due to the increased number of API calls and heavier responses in 4.9+  every additional request compounds the latency over the internet. However the root cause is clearly on the emby side, as 4.8.11.0 handles remote access without any such issues on the same hardware and connection.

[pwhodges 2072]

45 minutes ago, leshkraven said:

On shows that contain only one season folder and a Specials folder, Emby is incorrectly treating them as single-season shows and flattening all episodes into one view instead of displaying separate season folders. This issue is also present on 4.8.11.0.

This is a user setting "Preferred TV Show Display" in your personal display settings:

You can select to always show season folders, show season folders only when there is more than one season, or never show season folders.

Paul

[leshkraven 3]

I am fully aware of that feature and did mention it with image. The issue is that it isnt working correctly when "Specials" folders S00 are introduced