Firefox 52.6 is scheduled to be released on January 23, 2018. Reporting this bug to track spectre mitigation inclusion progress.
In accordance with https://blog.mozilla.org/security/2018/01/03/mitigations-landing-new-class-timing-attack/
Firefox 52 ESR does not support SharedArrayBuffer and is less at risk; the performance.now() mitigations will be included in the regularly scheduled Firefox 52.6 ESR release on January 23, 2018.
Moved into bug 645510.
*** This bug has been marked as a duplicate of bug 645510 ***