How to use the MicroProfiler on Roblox transcript

hi everyone it's Andrew from roblock in this video we'll dive into the micro profiler what it is and why it's so powerful we'll get oriented troubleshoot a performance issue and even do some math everyone loves math the micro profiler is a performance optimization and troubleshooting tool rather than higher level averages like frames per second the micro profiler lets you get down to the well micro level you can examine individual frames and all of the processes that make up those frames as you might imagine this level of detail comes with a bit of complexity I'm using Studio here for convenience but the best place to use the micro profiler is in the Roblox client on the lowest end device that you want to support to open the micro profiler press control F6 on Windows or command F6 on Mac OS you'll see a bunch of bars appear at the top of the screen each bar represents one frame from your experience with new frames flowing in from the right the height of each bar indicates how long it took to render the frame hover over any bar for more information the real power of the micro profiler though is in detailed mode press contrl P or command P to pause which automatically switches you to the timeline from there you can left click and drag to pan in any direction on a modern computer with many CPU cores you might need to pan up and down quite a bit to find threads that are doing anything at all scrolling zooms you in and out with the green indicator on the graph showing your zoom level to jump to a particular frame right click it on the graph each colored label on the timeline represents a process something your experien is is doing as part of rendering that frame wider labels represent processes that took longer to complete when you see a label directly underneath another label that means you're looking at a child process a process that runs as part of the process above it because parent processes can't finish until all their children do you often want to troubleshoot the longest running lowest level child processes if you're asking what are all these processes anyway me too there are hundreds of them and it's hard to keep them all straight so we documented the most important ones at create. roblox.com Link in the description if the level of visual clutter is too much use the groups menu to filter the list of visible labels until you get to something more manageable let's examine a more concrete scenario generally speaking we want Roblox experiences to run at 60 frames per second there are 1,000 milliseconds in a second so if we divide 1,000 by 60 we can see that we want a new frame every 16.67 milliseconds if we get 59 frames after 10 milliseconds and then one frame after 410 milliseconds that causes a huge jarring stutter even though the math works out to 60 FPS so consistent frame times are more important than average frame rate this experience doesn't feel quite right even though the frame rate summary usually says 60 FPS if we open the micro profiler we can see these frame time spikes remember we want consistent frame times so even at a glance right after opening the micro profiler we know something's wrong some frames are taking way way way longer than others if we examine one of the smaller frames nothing jumps out but if we look at one of the slow frames whoa there we can see this massive process in one of the worker threads and in particular a label called Shady Rays the micro profiler provides a lot of clues for where to look Shady Rays is a script running under runs service. heartbeat and the problematic code seems to have to do with rayc casting search for shady rays in the Explorer open it and examine the code we can see the same run service. heartbeat event that we saw on the mic profiler so we know we're on the right track this script is short but if it were long or complex we could wrap portions of it in debug profile calls in this case though the culprit seems pretty clear so let's comment out the function and see what happens now our frames are all arriving in about 16.67 milliseconds and camera movement feels consistent and smooth this time all we had to do was comment out some code but in other cases you might need to reduce the number of light sources modify your environment to prevent High transparency overdraw or spread a particularly intensive calculation across many frames for more information on using the micro profiler to optimize your experience check out the documentation at create. roblox.com thanks for watching [Music]