Benchmark and Meltdown/Spectre mitigation on old intel CPU

I recently had a forced updated for the OS of my pc, moving from Win7 to Win10 on my old still rocking, high-end, "Sandy bridge" cpu.

During this operation (the IT service did this, not me) the CPU microcode get an update. I don't know if this is thanks to a bios update or an os update, the only things I know is I get a new microcode revision. I get the info from CPUID software, I did a doble check after/before the computer get away from my desk to know what appened under the hood, and this information confirms the good idea I had.

I think there's something about Meltdown/Spectre Intel CPU issue on this, maybe the "speculative memory acces" get denied with the microcode update, so the result is a very bad performance on the "LU test", the first test of the bench istruction. Now it's twice the time comparing a month ago. I think this test is for Regula memory access, so I'm wondering about some speculative memory access acceleration on these intel cpu istruction execution.

Does anyone of you get this "Lu test" performance drop?