As part of 1.21.5’s rendering changes, the game stopped resizing and recreating the data inside of vertex and index buffers using glBufferData each time they needed to be uploaded and began to instead update the buffer’s data via glBufferSubData.
The problem is that on macOS (and potentially with other systems and drivers), the pipeline gets flushed when glBufferSubData is used which forces rendering to wait until that operation has completed and flushing the pipeline is very slow. I’ve observed this resulting in the loss of around 50-75% of my FPS depending on how frequently the vertex and index buffers are being uploaded. This issue can be especially slow with rendering the HUD as that can require that the vertex and index buffers be uploaded frequently for being drawn.
Code Analysis
The code responsible for uploading vertex and index buffers is located at GlCommandEncoder#writeToBuffer in Mojmap.
Inside this method there are three paths available for the given buffer to be uploaded, the first one uses glBufferSubData, the second uses glBufferData, and the third path uses both. Prior to 1.21.5 the second path was chosen for uploading the given buffer which avoids this issue, now due to 1.21.5’s changes in the rendering pipeline, the first path using glBufferSubData is the chosen one which triggers this performance regression.
Fix
The old method of simply resizing and recreating the vertex/index buffer data when uploading it does not force the pipeline to be flushed, thus reverting this change or providing a workaround for affected systems is enough to resolve the significant performance regressions caused by this issue.
Environment
MacOS 15.3.2 with M1 Pro chip
Linked issues
is duplicated by 11
MC-295889
1.21.5 degrades performance
Resolved
MC-295978
Significant drop FPS on newest update
Resolved
MC-296005
Major lag after Update 1.21.5
Resolved
MC-296013
Major Lag in version 1.21.5
Resolved
MC-296126
Significant performance regression in 1.21.5 compared to 1.21.4
Resolved
MC-296188
Java Edition 1.21.5 Frame Drops
Resolved
MC-296314
Performance after 1.21.5 upgrade
Resolved
MC-296349
Large drop in FPS between 1.21.4 and 1.21.5
Resolved
MC-296497
FPS significantly decreased
Resolved
MC-297513
Minecraft Lagging after updating to 1.21.5
Resolved
MC-298606
Frame Rate Issues on ARM64 on 1.21.5
Resolved
relates to 2
Attachments
Comments 65
The performance tanked a ridiculous amount for me, I don't feel like I can enjoy the game as much while it continues to run this poorly.
I'm running 1.21.5 on an Apple M3 Pro MacBook Pro with 18GB RAM and the game is almost unplayable for me now when I am in my single player base near a lot of entities. On 1.21.4, I had absolutely no problems, but now, I have very poor FPS. Others are reporting this issue running 1.21.5 on Apple Silicon in this Reddit thread.
Yes, I am the person who made the reddit thread above, I was making 130fps generally on realms, now dropping to, like the post and video within shows, 8/9fps… This is absurd… This “upgrade” has only been a “downgrade” for me
1.21.4 ran smooth as butter for me with “fancy” settings throughout. Since 1.21.5 the game is literally unplayable, even with everything switched down to lowest settings. This is on Java Realms with no mods/shaders/resource packs.
Happy to provide further info as needed.
Just to add to my last comment - I am on PC, rather than mac. Felt worth adding as the reddit thread is specifically on mac machines.
It is probably more so an ARM CPU issue rather than only Mac machines, it’s just the CPU architecture is more common in modern Macs
I’ve also tried to increase my allotted RAM and even at 10% utilization, I’m running at 10fps in areas of the game with a lot of entities. This version of the game is unplayable on ARM CPU machines. I am so hoping they rollout a patch soon and we don’t have to wait for a new version.
I noted similar issues in MC-295828 but I think mine came first
Yours is very technically detailed though so I hope it doesn’t get marked as a duplicate or anything lol
@amthyst_ It looks like the Mojang team wants this to be the main ticket, so I encourage you to upvote this ticket. It will be more clearly a priority for them to address if one Jira ticket has a lot of attention vs. the same issue being flagged in multiple tickets.
I did upvote this ticket.
I did find about a 15% performance decrease on my Intel/AMD windows pc.
which is an x86 system mind you so this isn’t exclusive to macs & arm64
Same issue here, FPS dropped from 120-150 to 30-80 on my Macbook M1
Same issue on a Macbook M3 Pro. I have a pyramid with 1570 world maps mounted in frames on the floor. My framerate drop seems to be proportional to the number of maps in my view. Less than 10 fps when I have most of them in view, making it almost unplayable. I did not observe this problem in 1.21.4, it is new with 1.21.5.
Totally agree, MacBook Pro 2022 M1, went from 130-80fps to 28-8fps… With this upgrade not adding too much, this upgrade truly was a downgrade…
Issue also on AMD Ryz5 with RTX3060, drop in FPS of about 15 to 20%
with huge spikes in FPS-decrease when entities appear in POV
same issue on msi bravo 15 c7udx with RTX 3050, fps drops drastically and huge fps drops at random times sometimes as low as 5 fps, very laggy. 1.21.4 works perfectly fine.
Same thing here game is unplayable as it is pls fix this!
I'm on ipad air 5 and it gets choppy. Everything normal but every 20 seconds or so it freezes for a second.
@Andres Merida I don’t think PojavLauncher is officially supported by Mojang.
I'm playing with sodium and low performance in everything with at best 40fps and frequent lag spikes. Before this update I would be getting 200fps lowest maybe 50fps with the same setup.
I’m on a macbook pro M4 and it’s basically been unplayable since the update. Every minute ish frames just drops to 1/freeze and unfreeze a second or two later. I thought it was me that had done something wrong but this seems more likely.
[JAVA] Full AMD system here, went from 120fps to 30 at best in 1.21.5.
I am experiencing anywhere from a 15% to 30% lots in framerate going from Minecraft (Java Edition) 1.21.4 to 1.21.5. The impact was consistent on the two systems I tested with.
Both systems are AMD Ryzen systems; a desktop with an NVidia RTX 2070 and a laptop with an AMD RX 7700S
Happens for me as well, on an AMD Ryzen 7 7700x and 4060ti
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No performance degradation on my system, in fact I sometimes seem to have significantly better FPS on 1.21.5 than on 1.21.4
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I’m on Windows 11, X86_64, using a (laptop) Nvidia 3080. My FPS drop is ~50% between 1.21.4 and 1.21.5, and from bisecting the snapshots the issue seemed to have been introduced in pre1
Still having this issue on all 1.21.5 and all snapshots thereafter so really hoping Mojang fixes this 😞
Why this is still a thing? Those FPS drops makes game unplayable
This is unplayable. I’ve had to wait 5 minutes for loot to drop after I broke a block. I’ve been teleported to spots that I was a few minutes ago. I’ve also waited 3 minutes for a small chunk to load, just to walk 7 blocks forward before having to wait another 3 minutes for the next chunk to load. Please fix this.
Also big fps drop for me, with high usage and higher temperatures, please fix it asap
Win 11, ryzen3 3100, gtx 1650 super, 4gb ram allocated setup
ryzen 7 7800x3d and rtx 4080 super - I get 20 fps when looking at about 20 chickens 🙂 It has not happened on 1.21.4
Please fix my friends
1.21.5 is lagging both singleplayer worlds as well as a server I host (which has more than enough resources) I have an i7-12gen 4070TiSuper 32gb ram running the game off of an NVMe, I should be having no issues and I wasn't on 1.21.4
Please fix this asap
I do not think the regressions highlighted in this report are the main or even a major source of decreased performance on some hardware.
There’s been a PR made to Sodium to revert this exact change and in my case (Intel Arc GPU) it did nothing to adress the regressions
https://github.com/CaffeineMC/sodium/pull/3094#issuecomment-2770246790
Upgraded and regret it. Even with all the mods i was running - never had any lag. Now 1.21.5 with absolutely NO mods is so laggy that I have to avoid my own base. FIX ASAP!
Correction - FIX IMMEDIATELY! Shouldn’t have been released with this much lag.
I use a Mac from 2017 and my world has been lagging a horrible amount since updating with very low fps that makes it difficult to move or turn around. If Mojang doesn’t release a fix I’m afraid I’ll have to revert back to 1.21.4 where it was working fine and unfortunately be unable to play this new update even though I was really looking forward to it.
1.21.5 lags in motimaa and oplegends, but hypixel works fine
1.20.6 is ok in oplegends
singleplayer works fine
Been trying to play on my 2022 macbook air and im getting less than 20fps on multiplayer without mods
after updating can't do anything, lag spikes are so bad without a cause and it makes it unplayable be it multiplayer or singleplayer..
Having the same issue. Was averaging around 170FPS in 1.21.1 on our multiplayer. Now get around 150FPS in the same spot.
Same problem here. Getting significantly worse fps compared to 1.21.4 version
Same problem here still to this day, literally unplayable as it gives me motion sickness now
Same
This is really annoying issue!!!!
Fix it please
Affects 25w19a
I commented on Apr 19, and the problem is still persisting today on May 6. I’m getting about 20 FPS on my MacBook Pro. This is significantly worse performance than 1.21.4, where I was getting around 45-65 in the same area. This happens on multiplayer and singleplayer.
Please fix this issue soon, it’s making it next to impossible for me to play as everything moves so slowly with the lag and it is really disappointing.
For the time being the fabric mod ‘ImmediatelyFast’ fixes this issue
Also same. 1.21.5 gives me like 40 less FPS compared to 1.21.4 with complementary shaders on the same settings lol
And ImmediatelyFast does not counter-act the FPS loss from 1.21.5.
I cannot believe this is still not fixed. 😕
Affects 20w25a
I meant 25w20a, sorry.
yeah, it was so bad that I reverted it to a previous version. Was really sad to lose the new flowers and the new animal skins.
I need a fix for `1.21.5`. It’s unplayable with shaders for me.
Insight from RaphiMC:
”The buffer upload regression in 1.21.5 does not affect all systems. It mostly affects Apple GPUs. Avoiding glBufferSubData on all systems causes a performance decrease on most GPU drivers. ImmediatelyFast <=1.21.4 in fact even has an optimization which replaces glBufferData with glBufferSubData because its measureably faster on most systems.
It should be noted that 1.21.5 has multiple other performance regressions, even ones which affect all GPU vendors, so direct comparisons between 1.21.4 and 1.21.5 even with the buffer upload fix are not possible.”
Affects 25w21a
@Ceresjanin123 Unfortunately I am part of the population who uses nvidia GPUs (RTX 4060 Ti) and is still impacted by this regression hard.
I am able to play 1.21.4 very happily at 720p on a raspberry pi 5, around 60fps in most cases. I upgraded to 1.21.5 and it’s unplayably slow at all the same settings, less than half the framerate and crashes when traveling fast. Was psyched to have a really low power computer that could play this game, would love to get the performance from 1.21.4 back!
I tried the Snapshot 3 version of 1.21.6, still not fixed.
I will mark this as Plausible since I can confirm that 1.21.5 does seem to bring a performance regression (in the screenshots below, it’s roughly 15-20%, but I would believe it could be much higher depending on the situation).
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