There is no indication to the user, that in this case wasn't even aware the experiment was active ... (actually the user didn't know about at experiments at all, but found that the support article [Firefox's performance settings](https://support.mozilla.org/en-US/kb/performance-settings) had an extra option that was not being shown). Please remember that this was a completely new user with a pristine profile. Could you still show the option to set the number of processes, but greyed out? To just remove it from the UI makes it difficult to know what happened. A new user without knowledge of experiments has no way of knowing what is wrong (related to the support article) in one new Firefox compared to another new Firefox. It took quite some time for me to find out what the actual issue was. I think that experiments should be allowed to do only so much behind the scenes without letting the users know. Silently removing parts of the UI should probably not be among the available options, taking into account that users might not even know they are running experiments, let alone know what they might be doing.
Bug 1742892 Comment 2 Edit History
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There is no indication to the user, that in this case wasn't even aware the experiment was active ... (actually the user didn't know about experiments at all, but found that the support article [Firefox's performance settings](https://support.mozilla.org/en-US/kb/performance-settings) had an extra option that was not being shown). Please remember that this was a completely new user with a pristine profile. Could you still show the option to set the number of processes, but greyed out? To just remove it from the UI makes it difficult to know what happened. A new user without knowledge of experiments has no way of knowing what is wrong (related to the support article) in one new Firefox compared to another new Firefox. It took quite some time for me to find out what the actual issue was. I think that experiments should be allowed to do only so much behind the scenes without letting the users know. Silently removing parts of the UI should probably not be among the available options, taking into account that users might not even know they are running experiments, let alone know what they might be doing.