Thanks for the report.

+Hiroshige, +Kinuko: any thoughts on this? If it makes sense, is it easy to make the change (i.e. do we need to spend time estimating the impact to justify the work)?

I'd like to understand more background on this.

MemoryCache doesn't hold any strong references to the resources now.
Also, MemoryCache contains Resource, which contains decoded content.
The fact that the content can be easily fetched again w/ low cost isn't enough to justify (svg images are small in raw bytes, but has non trivial decoding/rendering cost).