Does use of memory with timing CL=10 instead of Apple used CL=11 slow my Mac down?

After reading Why is 8GB, Ballistix 204-pin SODIMM, DDR3 PC3-12800 memory module showing as not compatible with Macbook Pro mid 2012? on the Crucial forum, and the response from Crucial:

use our Apple branded Crucial memory

which doesn't explain the why it is not compatible,

I am curious whether memory modules that use different (lower) timings than Apple's modules with CL11 timing:

1. Will the Crucial Ballistix BX Sport CL10 [BLS8G3N18AES4CEU/BLS2C8G3N18AES4CEU] modules work?
2. And what will be the performance penalty or benefit?

Solution 1:

Yes, Crucial Ballistix Sport memory modules with CL=10 timing do work.

The results of an Xbench 1.3 "Memory Test":

1. Hynix CL=11: 618.25
2. Crucial CL=10: 699.12

The not by Crucial recommended memory modules perform 13% faster then Apple's factory default modules in this Mac.

Benchmarking performed on a 15" MacBook Pro (Mid 2012, MD103xx/A, MacBookPro9,1) with 2 modules of identical memory:

1. Apple default Hynix HMT325S6CFR8C-PB (PC3-12800S (DDR3-1600)
2. Crucial Ballistix Sport BLS2C8G3N18AES4CEU (PC3-14900 (DDR3-1866))

Detailed results:

1. Hynix

   • Memory Test: 618.25
   • System: 679.54
   • Allocate: 2388.91 (8.77 Malloc/sec)
   • Fill: 414.93 (20174.73 MB/sec)
   • Copy: 630.47 (13022.12 MB/sec)
   • Stream: 567.11
   • Copy: 569.11 (11768.32 MB/sec)
   • Scale: 571.98 (11817.02 MB/sec)
   • Add: 568.58 (12112.06 MB/sec)
   • Triad: 558.29 (11943.20 MB/sec)

2. Crucial

   • Memory Test: 699.12
   • System: 699.53
   • Allocate: 2327.00 (8.55 Malloc/sec)
   • Fill: 435.50 (21174.97 MB/sec)
   • Copy: 639.94 (13217.72 MB/sec)
   • Stream: 698.71
   • Copy: 689.46 (14240.61 MB/sec)
   • Scale: 695.49 (14368.67 MB/sec)
   • Add: 716.26 (15257.79 MB/sec)
   • Triad: 694.24 (14851.47 MB/sec)