Play has a memory leak

[cedaraspen]

carlop3k: playpens seems to have a memory leak; when testing UI's and doing many changes for at least 20 minutes or more usage goes up to 1.5GB; i'll try to reproduce it again on Firefox

carlop3k: this seems to happen when i modify many times a / container, oddly enough when i pass the profiler just shows as always idle

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Internal reference: DX-6284