TestRoomKeyIsCycledOnMemberLeaving flake due to tabs?

[kegsay]

      room_keys_test.go:281: [@user-133-alice:hs1](js) SendMessage !XxmQBbvEwyZPcwXBRN:hs1 => $FDtbPtEoxfcSoOieK88Ztghpl49OmRAvO5zxWEK_J6I
      room_keys_test.go:282: @user-134-bob:hs1 (js): Wait[!XxmQBbvEwyZPcwXBRN:hs1]: timed out: bob did not see alice's message

Logs show CC: lines for the Waitf call as it does getLiveTimeline and logs each event. It does not show /sync returning any response before it times out 5s later.

Logs before Waitf:

14:42:31.333184Z [@user-134-bob:hs1,SQMAZNGJZF] console.log FetchHttpApi: --> GET http://127.0.0.1:32814/_matrix/client/v3/sync?filter=xxx&timeout=xxx&since=xxx
14:42:32.283290Z [@user-134-bob:hs1,SQMAZNGJZF] console.log TestRoomKeyIsCycledOnMemberLeaving/{js_hs1}|{js_hs1}: [@user-134-bob:hs1](js) WaitUntilEventInRoom !XxmQBbvEwyZPcwXBRN:hs1

This is on the client-as-tab PR, so I wonder if Chrome is throttling the tab..?

[kegsay]

Another flake, this time on TestRoomKeyIsCycledOnMemberLeaving/{rust_hs1}|{js_hs1}

       rust.go:788: [@user-139-alice:hs1]TimelineDiff change: &{ID:$Xvk7Sd8eKEQ3f2AgYhmTZKQaSiPnRezObph99MMxDB0 Text:Another Test Message Sender:@user-139-alice:hs1 Target: Membership: FailedToDecrypt:false}
      room_keys_test.go:282: @user-140-bob:hs1 (js): Wait[!wNugXDgsubWzwaFNAx:hs1]: timed out: bob did not see alice's message

And again on js/js:

       room_keys_test.go:281: [@user-133-alice:hs1](js) SendMessage !NbXBhaSlSPoxxcKtAQ:hs1 => $u593PV7pwIHenPEYHJBjPfv_gBAV9qRzW_mqD7J2b7I
      room_keys_test.go:282: @user-134-bob:hs1 (js): Wait[!NbXBhaSlSPoxxcKtAQ:hs1]: timed out: bob did not see alice's message

06:56:34.330273Z [@user-134-bob:hs1,UVIQGNBWDF] console.log FetchHttpApi: --> GET http://127.0.0.1:32814/_matrix/client/v3/sync?filter=xxx&timeout=xxx&since=xxx
06:56:35.281967Z [@user-134-bob:hs1,UVIQGNBWDF] console.log TestRoomKeyIsCycledOnMemberLeaving/{js_hs1}|{js_hs1}: [@user-134-bob:hs1](js) WaitUntilEventInRoom !NbXBhaSlSPoxxcKtAQ:hs1

This only happens on #108 so there must be something about tabs causing this.