Intuitive Debugger: Absurdly Slow Debug

Since yesterday, when Roblox arbitrarily imposed (a second time) the new Intuitive Debugger as the only debugger (not giving you the option to switch back to the old debugger), debugging has become virtually INVIABLE.

In the video below, you can see that each debugging step takes around 3 to 4 seconds, between moving to the next line and updating the other windows (Watch and Call Stack):

And, the longer the list of variables in the Watch window, THE SLOWER THE DEBUGGER WILL BE.



To make it clearer about this absurd slowness of the new debugger, the problem is mainly related to the new debugging windows opened:

  1. Breakpoints
  2. watch
  3. Call Stack

As you can see in the video below: when the above windows are OPEN, each step in the debugger takes 3 to 4 seconds (until the content of each window is updated).
When these windows are CLOSED, each step takes only around 0.5 seconds:

This is the MAIN cause that is making it impossible to use the new debugger.

In time: these WINDOWS are also causing a GENERAL SLOWNESS in the execution of a script, as reported here:

Interesting. This bug was prioritized to be looked at this week so this insight is helpful, as it narrows down where to look for the performance bottleneck. Thanks for your help.


Any news on this biggest Intuitive Debugger issue?
I confess that I had to abandon this new debugger, even with all my efforts to raise all the more than 20 bugs that I already reported; but slowness is something that simply makes this debugger unfeasible.

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Hi rogeriodec_games,
As far as the the debugger performance bottlenecks go, this week we will be turning on a fix which removes the slowdown in performance when adding values in the My Watches tab. In addition, we will be turning on fixes for Intuitive Debugger: not showing the instance name in front of all properties when hovering a variable and Intuitive Debugger: Keyboard shortcuts for some windows won’t work during debugging . We are actively triaging the bugs that you report and working on improving the debugger, and appreciate your patience.


Despite the disclosure of a possible performance improvement in the Watch window…

…debugging continues to be extremely slow.

The video below clearly shows the problem:

  1. When the 3 windows are open (Watch, Breakpoints and Call Stack), each step takes 2 seconds.
  2. Closing the Call Stack window, the time improves a little, something around 1.8 seconds at each step;
  3. Closing Breakpoints, time drops to just over 1 second at each step;
  4. Closing Watch (no debug support window), the time is similar to the old debugger, ie just under 0.5 seconds per step.

This shows that the problem is not in the debugger itself, but that debugger slowdown has to do with open debug secondary windows

In over 40 years of IT, I’ve never come across a debugger this slow.
I insist that this is UNVIABLE.
However, Roblox has insisted on ignoring developer feedback.

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I avoid using the debugger because of the painfully slow performance on a powerful computer, as a frequent user of the old debugger. This is even without the Watch or Call Stack windows open.

I’m a little concerned that there may be architectural performance problems with it, because I was told when I raised concerns early in the beta that this would be improved.


This “architectural performance problems” concern is accurate.
Since the new debugger uses Lua for its UI instead of C++, it is subject to the Studio Lua rendering pipeline. Our investigation from user reports such as this helped to uncover a Lua rendering bottleneck that exists Studio-wide on an architectural level. Unfortunately, as a result, fixing this slowdown is a gradual process that takes time and work from all Studio teams. However, it should eventually result in a speedup for not just the debugger, but for all of Studio.


I already imagined that, but it’s hard to believe they chose Lua for a critical process…
Sorry, this is a disaster and as I understand it, the debugger should be COMPLETELY REWRITTEN.
If something urgent takes months, it will apparently take YEARS.
Meanwhile, anyone who wants to be a Roblox developer has to settle for that…

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Thanks for the transparency! It’s great to know there are plans to address this.

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Below, another example of how the 3 debug windows are DRAMATICALLY affecting graphics performance:

My computer crashed and I had to fix it.
After a week off, after reinstalling all Windows 10 from scratch and everything, I went to test the debugging and, to my surprise, it was faster.
I ask: was anything fixed by you during this period? Or would this slowness have something to do with a problem with my previous Windows?

I don’t know of any significant speedup work recently that would affect the debugger, so the fresh Windows install would likely be the culprit.

Thanks for your feedback.
However, if the slowness problem was only on my side, don’t you think someone should have warned me?
That would have saved everyone a lot of time.
What seems then is that no one has looked into this problem so far, because if they had carried out the same simulations that I proposed, they would have verified it immediately.
Now, if someone on your end has tested it and managed to get the same slowdown, then it’s not an issue on my end.

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