We haven't noticed anything that is consistently slow in the past couple days, but it's definitely happened multiple times in the past!
Even without an "Enterprise" tier plan you have several tools that may help, but I agree with Mark and you should open a Support Ticket who has a suite of tools and workflows to take a deeper dive.
In the interim, you may want to consider heading over to you QB Admin Console (click "My Apps" and "Manage My Account" in sidebar) where you can think review Platform Analytics. This sub-links out to various filterable reports. For example, filter Integration or User Reads by date range.
In "App Management" there is also a "Performance management" link that will list known issues and assign them a severity (priority).
I also typically check the Quickbase Status page for any reported issues.
You can also head over to the your "App Properties" and take a look at the Performance options checkboxes. You can enable the Show performance analyzer and then run that bad boy.
Aside, from noisy neighbors, and I'd also check a few other things within your control, including table record volume which I've seen become an issue in larger apps with over a million records in a given table.
Also, if you go into you "Fields" listing on a given table and then click "Advanced Options" (top-right), you can check the boxes for "Reportable" and "Searchable." I suggest going through each table and unchecking Searchable for a many of those as possible for you use case. I don't think Reportable will impact performance, but I try to tidy that too while I'm there. And in the process review the "Default Report Settings" for each table and select the "don't make it a default column" radio option (When a new field is added to this table). The idea here is to only search the bare minimum necessary.
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Brian Seymour
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