The ACSC's advice remains that organisations should patch Meltdown/Spectre vulnerabilities as soon as possible.
Vendors have advised that in most cases there will be negligible performance impact following the application of the patches. For everyday users, the performance impact of applying these patches is unlikely to be noticeable.
Should organisations still be concerned about performance impacts, the ACSC recommends that you consider patching and testing plans in your environment prior to application.
For more detailed information, see 5 January 2018 update below.