# Whether there will be a performance impact, If we subscribe for large amount of tag value change (e.g. 20k)

**URL:** <https://forum.inductiveautomation.com/t/whether-there-will-be-a-performance-impact-if-we-subscribe-for-large-amount-of-tag-value-change-e-g-20k/62824>\
**Category:** Ignition\
**Tags:** ignition81\
**Created:** [August 9, 2022, 2:13pm UTC](https://forum.inductiveautomation.com/t/whether-there-will-be-a-performance-impact-if-we-subscribe-for-large-amount-of-tag-value-change-e-g-20k/62824 "2022-08-09T14:13:23Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Salman\_Faris](https://avatars.discourse-cdn.com/v4/letter/s/d2c977/32.png) [@Salman\_Faris](https://forum.inductiveautomation.com/u/Salman_Faris)\
**Post date:** [August 9, 2022, 2:13pm UTC](https://forum.inductiveautomation.com/t/whether-there-will-be-a-performance-impact-if-we-subscribe-for-large-amount-of-tag-value-change-e-g-20k/62824/1 "2022-08-09T14:13:23Z")

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In my module, I have a requirement to listen for the change in tag value for around 20K PLC tags inorder to validate the tag value.  
I am worried does subscribing for 20K tag change listeners will create an Performance impact?  
If so, what could be an alternative approach?

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**Author:** ![paul-griffith](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/paul-griffith/32/37249_2.png) [@paul-griffith](https://forum.inductiveautomation.com/u/paul-griffith)\
**Post date:** [August 9, 2022, 4:45pm UTC](https://forum.inductiveautomation.com/t/whether-there-will-be-a-performance-impact-if-we-subscribe-for-large-amount-of-tag-value-change-e-g-20k/62824/2 "2022-08-09T16:45:43Z")

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The performance impact is probably going to be felt more by the device(s) you’re subscribing to than by Ignition.

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**Author:** ![gmabalot](https://avatars.discourse-cdn.com/v4/letter/g/b5a626/32.png) [@gmabalot](https://forum.inductiveautomation.com/u/gmabalot)\
**Post date:** [August 9, 2022, 6:45pm UTC](https://forum.inductiveautomation.com/t/whether-there-will-be-a-performance-impact-if-we-subscribe-for-large-amount-of-tag-value-change-e-g-20k/62824/3 "2022-08-09T18:45:49Z")

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This depends on your Ignition server specs, network architecture, and PLCs. Have you tried testing this in an isolated environment?

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**Author:** ![Salman\_Faris](https://avatars.discourse-cdn.com/v4/letter/s/d2c977/32.png) [@Salman\_Faris](https://forum.inductiveautomation.com/u/Salman_Faris)\
**Post date:** [August 11, 2022, 9:25am UTC](https://forum.inductiveautomation.com/t/whether-there-will-be-a-performance-impact-if-we-subscribe-for-large-amount-of-tag-value-change-e-g-20k/62824/4 "2022-08-11T09:25:13Z")

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We are using a server spec of 4 Cores, 16GB memory with standard ignition archtecture as recommended by Medium ignition Project([Ignition Server Sizing and Architecture Guide | Inductive Automation](https://www.inductiveautomation.com/resources/article/ignition-server-sizing-and-architecture-guide))