performance considerations or common pitfalls to watch out for?

[eva753kimso]

Hi everyone,

Are there any performance considerations or common pitfalls to watch out for?

[M Iftikhar]

Hi Eva,

Great question! Yes, there are several performance considerations and common pitfalls to keep in mind when working with ServiceNow:

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 Performance Considerations

• Avoid Unnecessary GlideRecord Queries

  • Always query on indexed fields (e.g., sys_id, number).

  • Use .addQuery(), .setLimit(), and only return required fields.

  • Avoid getRowCount() on large tables; use aggregate queries or pagination.

• Use Asynchronous Processing

  • Heavy logic should run via Scheduled Jobs, Events, or Flow Designer background actions, not synchronously in Business Rules.

• Leverage Caching

  • Use out-of-box caching mechanisms (e.g., GlideAggregate, session storage) for data that doesn’t change often.

• Minimize Client–Server Calls

  • Bundle data in a single GlideAjax call rather than making multiple round trips.

• Optimize Related Lists & Forms

  • Limit rows in related lists (100+ can slow pages).

  • Reduce excessive onLoad/onChange Client Scripts or UI Policies.

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Common Pitfalls to Avoid

• Editing OOB Objects

  • Avoid modifying OOB Business Rules, ACLs, or Tables. Clone or extend instead, keeps upgrades safe.

• Unoptimized Scripts

  • Nested loops or excessive gs.info() logging inside frequently triggered Business Rules can slow performance.

• Complex ACL Scripts

  • Overly heavy ACL logic increases both performance cost and maintenance overhead.

• Unrestricted Scheduled Jobs

  • Large jobs running in production during peak hours can impact instance health. Break them into smaller chunks or run off-peak.

• Skipping Sub-prod Testing

  • Always test heavy queries or logic in a sub-production instance with realistic data before deploying to prod.

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Best Practice:

• Use indexed queries + caching for efficiency.

• Run heavy logic asynchronously instead of inline.

• Keep scripts modular and lightweight.

• Always test in sub-production and use System Diagnostics/Performance Dashboard to identify bottlenecks.

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Hope this helps!
Thanks & Regards,
Muhammad Iftikhar
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