A ThroughputLimiting plugin would limit the amount of RAM and CPU used by the image resizer at any point in time, causing requests to queue (or be cancelled) instead of executing all at once.

If your application accepts batch uploads, this could be very helpful in keeping RAM usage low enough. On a 32-bit application pool, RAM usage is limited to 2GB, which equates to 200-500MB/s of resizing throughput. With 200 concurrent uploads of 20MB files each (and with a client who has an insanely fast fiber or ethernet connection), it's possible to exceed this.

If you're using shared hosting, you may have less than 2GB to use.