Eliot Miranda uploaded a new version of System to project The Trunk:
http://source.squeak.org/trunk/System-eem.1181.mcz

==================== Summary ====================

Name: System-eem.1181
Author: eem
Time: 16 October 2020, 10:55:23.59864 am
UUID: 46d93234-f04b-4b34-9730-972c0c5876ac
Ancestors: System-mt.1180

Indexed access to registered external objects, avoiding the overhead of copying the entire external object array.

=============== Diff against System-mt.1180 ===============

Item was added:
+ ----- Method: ExternalObjectTable>>externalObjectAt:ifAbsent: (in category 'accessing') -----
+ externalObjectAt: index ifAbsent: errorBlock
+ 	"Answer the externalObject at index, or the result of errorBlock if none."
+ 
+ 	^(semaphore critical: [externalObjectsArray at: index ifAbsent: nil]) ifNil:
+ 		[errorBlock value]!

Item was added:
+ ----- Method: SmalltalkImage>>externalObjectAt:ifAbsent: (in category 'external objects') -----
+ externalObjectAt: index ifAbsent: errorBlock
+ 	"Answer the externalObject at index, or the result of errorBlock if none."
+ 
+ 	^ExternalObjectTable current externalObjectAt: index ifAbsent: errorBlock!