Various transaction quota rules are available in the base system.

Fix Script Processor
Allows the fix script processor to run for four hours.
Presence
Cancels presence requests quickly when the system is busy.
REST Import Set API request timeout
Prevents inbound REST Import Set API transactions from running for longer than 60 seconds.
REST Table API request timeout
Prevents inbound REST Table API transactions from running for longer than 60 seconds.
AMB Transactions
Cancels AMB transactions lasting longer than the specified maximum duration. Applies to all AMB transaction types: message send and message receive.
Reference Completer
Stops the reference completer transaction after five seconds.
REST Aggregate API request timeout
Prevents inbound REST Aggregate API transactions from running for longer than 60 seconds.
Homepage Widgets
Prevents all homepage widgets from running longer than 30 seconds.
REST Attachment API request timeout
Prevents inbound REST Import Set API transactions from running for longer than 60 seconds.
UA Count Persistor Quota
Prevents UA count persistor scheduled jobs from running for more than one hour.
UI Transactions
Cancels UI transactions that are two seconds away from the 5-minute server disconnect. ServiceNow datacenter load balancers display an internal server error (HTTP Error 500) to users after five minutes. This quota rule returns a transaction canceled page instead of an error. This rule includes an exception to prevent the cancellation of background scripts.
PA Diagnostics All
Prevents any Diagnostics transaction that originates outside the scope of the Diagnostics application from running longer than 30 minutes. Diagnostics transactions refer to executing a diagnostic, opening a Diagnostics form, or opening a Diagnostics list.

Normal transaction activities

Before setting transaction quotas, navigate to User Administration > Active Transactions to review the normal transaction activities for your instance. You can view and terminate long-running transactions if necessary. Over time, you can determine the normal transaction load for your instance and set your quotas to match these norms.