I’d recommend these articles:

Monitoring performance: https://help.acumatica.com/(W(5))/Help?ScreenId=ShowWiki&pageid=8f0a4339-6a33-469a-b916-50b893ca88e2

Troubleshooting performance: https://help.acumatica.com/(W(4))/Help?ScreenId=ShowWiki&pageid=1e173168-12d7-43cf-82e4-a140237a700c

Identifying the root cause of performance degradation: https://help.acumatica.com/(W(3))/Help?ScreenId=ShowWiki&pageid=11666144-db7d-4055-ad71-bd4906f4fc65

Generally my action plan for these is the following:

1. Check if the performance degradation is some specific process/area of the system or general across the system.
2. If performance degradation is in one specific place/process, check using Request Profiler if you can see what’s wrong (may be some heavy SQL requests, may be some customization)
3. If performance degradation is general, check if the system is used within the license constraints (see License Monitoring console screen), check the System Monitor screen to see if there are any running processes that are not expected or if the resource consumption is higher than expected.

Ahhh, the infamous performance query.  There’s a lot of things that can cause a user to question performance. Many times there’s items outside of your control, such as the users environment (Browsers, extensions, computer, bandwidth, etc.). The performance troubleshooting checklist that @Dmitrii Naumov shared is likely the best way to approach general performance related questions https://help.acumatica.com/(W(6))/Help?ScreenId=ShowWiki&pageid=1e173168-12d7-43cf-82e4-a140237a700c

However, if this is happening on a more generalized scale, I’d immediately start looking at the instance as a whole. Start tracking the information, what was going on when the issue arose, what were they doing, how many people were logged in and performing activities at the same time, etc.  You can find all of this in the Activity Monitor. Additionally, if they’re hosted vs PCS, tiered licensing model vs concurrent user license model, API connections and throttling.  These are all things that can affect “Performance”.  

Some other items to take note of, what version are they running, are the GI’s optimized, is this happening only on a specific report or every page in the system, is it just one user reporting the issue or many, was there a recent customization installed? There’s so many avenues to go down, getting to the bottom of the performance question can take a while, but it’s not impossible.

If you have more information, I’d be happy to help! 

Thanks,

James