Request execution time keeps increasing over time when using `Parse.Object.extend`

[mtrezza]

New Issue Checklist

• I am not disclosing a vulnerability.
• I am not just asking a question.
• I have searched through existing issues.
• I can reproduce the issue with the latest versions of Parse Server and the Parse JS SDK.

Issue Description

There are numerous reports that Parse Server execution time increases over time:

• Performance issue on version 4.x parse-server#7404
• Parse Server performance loss parse-server#7036
• Fetch large data for reports slow parse-server#6543
• Parse.Object.saveAll() get slower after each call parse-server#6300
• Saving 3000 objects in cloud code with saveAll takes more than 10 seconds parse-server#5471
• https://community.parseplatform.org/t/parse-server-performance-loss-after-time

The issue may well be a JS SDK issue if the code causing the issue runs in Cloud Code using the Parse Server-integrated JS SDK.

Steps to reproduce

See reported issues above.

Actual Outcome

Server request execution times increase over time.

Expected Outcome

Server request execution times should stay the same over time.

Environment

Server

• Parse Server version: various

[parse-github-assistant]

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