For the curious, you're likely using one or more extensions and thus multi-process won't be on when you update to it. Mozilla is rolling it out cautiously, so

For the curious, you're likely using one or more extensions and thus multi-process won't be on when you update to it. Mozilla is rolling it out cautiously, so everyone with any extensions at all is excluded and everyone with no extensions either has it on or is in the 'control group' which will be used to judge the affect that enabling multi-process has on stability based on telemetry reports from both groups.