TLB invalidation IPI timeout on El Capitan

The TLB (Translation Look-aside Buffer) is the heart and soul of any computer's virtual memory system. It is CPU chip hardware. The same hardware that Windows would be using for virtual memory, as well as Linux, Solaris, etc...

The TLB is very fast specialized memory that allows the CPU to hand it a virtual memory address, and the TLB will either tell the hardware memory fetching code the physical page of memory associated with that virtual memory. We are talking 1 clock cycle fast. If the TLB does not have the virtual to physical translation, then a soft page fault occurs, and the operating system gets to use lots of instructions to find the physical page associated with the virtual address, and then load that information into the TLB (and in the process ejecting some other TLB entry). Then the instruction is re-issued, and the TLB will now have the translation.

That is the TLB high level description.

Now why you got a panic, I am fairly sure it has zero to do with your new certificate. It is more likely a hardware failure. If this is happening a lot, then I would look at running the hardware Diagnostics

Use Apple Diagnostics to test your Mac - Apple Support