Editor has poor performance on beatmaps with many timing points

[kadoen]

This starts to happen even if there's just a few timing points/SV changes.
Framerate drops significantly and performing actions becomes quite laggy. I have mosly knowledge of osu!mania where I've detected the issue but I've also identified some osu!taiko beatmaps where the same thing happens, so I assume it's widespread across gamemodes.
Some example beatmaps:

• https://osu.ppy.sh/beatmapsets/702584#taiko/1873786 (SV)
• https://osu.ppy.sh/beatmapsets/821745#taiko/1722264 (SV)
• https://osu.ppy.sh/beatmapsets/512591#mania/1256061 (SV)
• https://osu.ppy.sh/beatmapsets/723633#mania/1527737 (SV)
• https://osu.ppy.sh/beatmapsets/1086739#mania/2272532 (BPM changes)
• https://osu.ppy.sh/beatmapsets/1432082#mania/2955326 (BPM changes)
• https://osu.ppy.sh/beatmapsets/1604686#mania/3342376

In the last example, it doesn't have a massive amount of SV and they are centered in 2 sections, but even looking at a part of the chart with no SV/timing points at all the performance is noticeably degraded.
I can give more examples if needed, any map with a decent amount of SV or a live performance (which requires many timing points) exhibits this problem.
It's also not related to the amount/density of objects, as I've tried some very dense beatmaps (such as https://osu.ppy.sh/beatmapsets/1182558#mania/2465481) and the performance is fine.

It's also worth noting the performance in gameplay is fine, the degradation happens only in the editor.

[bdach]

can you press ctrl+f2, then scroll down to the end and take a screenshot or capture a video of this? because on my machine it's not tragic (i still get ~120fps), although there are some obvious candidates for optimisation that look related:

[peppy]

Also can't repro. Needs logs and screenshots as above.

[kadoen]

lazer_editor_lag.mp4

Took a small video showing an example with one of the beatmaps linked above. Compressed the video to fit in github size but all details should be appreciable. (edit: for some reason looking at the video in-browser it looks worse in quality than downloading it, might be on my end) The performance is slightly affected by the screen recorder but there's not a significant difference.

Some of my specs in case they're useful:

• CPU: AMD FX-6300
• RAM: 8GB DDR3
• Motherboard: ASUS M5A97 LE R2.0
• GPU: NVIDIA GeForce GTX 750 Ti
• Storage: 1TB SSD Crucial MX500

I attach the performance log: performance.log

[bdach]

do you mind trying this again but with the default lazer skin and seeing if framerate improves? there is a good amount of evidence in that video there that this may not be the editor's fault per se rather than the legacy skin's. textures/sprites are not yet pre-loaded in the optimal way which may result in something like this.

[kadoen]

lazer_editor_lag_default_skin.mp4

Recorded the same set of actions now using the new default skin, with a similar result. I also attach the new log: performance.log

Even though it seems like it's not skin dependant, I attach the skin I normally use (and used in the first video) - Osu!Mania Skin+.zip

[bdach]

scratch above, i can reproduce with this map. https://osu.ppy.sh/beatmapsets/1604686#mania/3342376

initial profiling doesn't show anything obvious, though. need more time to investigate.

[peppy]

Can also repro with this one. Will investigate.

[peppy]

The overhead here is mostly GL/draw side, due to the summary timeline display:

It also has additional overheads on the timing screen, where input handling becomes a concern.

I am going to look at a potential improvement to the summary timeline for now, since that is always visible. The timing screen will require a bit more thought.

[peppy]

Will be resolved largely by #16446 if accepted. Note that this doesn't cover the timing screen itself.