Equipping / unequipping tools is causing FastCluster rebuilds

[MetatableIndex]

As per the Avatar Rendering Improvements from 8 months ago, tool equipping / unequipping shouldn’t cause FastCluster rebuilds. And yet… it is.

@chimig1984

Tools equipping or unequipping will not cause FastCluster rebuilds.

• To take advantage of this improvement, ensure that any Tools or accessories that you equip or add to an avatar do not have skinned meshes (i.e. Tools should have rigid parts only).

This is specially more noticeable when equipping / unequipping tools that contain a lot of triangles. (the performance implications are beyond the point; this is a bug report about the fact that FastCluster rebuilds are still happening even though they shouldn’t)

This can be reproduced in any place, including a baseplate. The screenshots in this post were taken in SCP: Roleplay.

Important note regarding the severity of this bug: we have no possible workaround for this since any workaround would imply moving away from tools and the entire game is built around the usage of tools. Even a keycard tool (1 part) causes this issue (albeit at a much smaller scale). If a player spam equips / unequips a tool, everyone around a radius of that player has FPS regression.

Additionally, Transparency updates are also still causing FastCluster rebuilds, but since that hasn’t been officially reported as implemented I haven’t made a separate bug report for it.

Repro script (run in server console):

local Player = game:GetService("Players"):GetPlayers()[1]

local a=Instance.new("Tool", Player.Backpack) local h=Instance.new("Part",a) h.CanCollide=false h.Name="Handle" for i = 1, 500 do local b=h:Clone() b.Name="Part" b.Parent=a local w=Instance.new("WeldConstraint") w.Part0=h w.Part1=b w.Parent=b end print'done'

A private message is associated with this bug report

[stormchaser9k]

@MetatableIndex

Hello, I have confirmed that the optimization we put in to skip rebuilding FastCluster is still working as intended in that it doesn’t rebuild the full avatar whenever equipping the tool. The ~1-2 ms updateGeometry time you are seeing in the Microprofiler is actually the optimized path that is doing the skip check, as otherwise without the optimization the time would be much higher.

I have tested SCP-Roleplay and checked your Microprofiler log as well.

If you have a reproducible rbxl file or case that produces much larger time cost, please attach it to the private message thread and I will take a look.

Also note that the transparancy (and color) change optimization has been rolled out for several months, so if you are still getting significant FastCluster rebuild time for transparency/color changes, please submit a reproducible case for us to debug.

[MetatableIndex]

Hi, thank you for reviewing this! I have sent additional information, including a repro file.

You are right that the Transparency and Color improvements have been functional for a while; however, for the specific case of tools, there seems to have been a regression, since I remember this having ceased to be a problem during that time. (and now it’s happening again)