Loss of performance for DGEMM with matrix dimensions ~1500 using MKL 11.1

Hello,

I'm using DGEMM from MKL 11.1 and Intel Composer XE 14.0.0.080 for benchmarking purposes. My system is a Intel Core i5-2500 and I run Debian GNU/Linux 64 bits. Attached I send the plots showing the DGEMM performance for some square matrices and for 1, 2, 3 and 4 threads. The problem is that I've detected a severe loss of performance for matrix dimensions of about 1500x1500. I said about because the behavior can be detected using dimensions fron 1300 to 1700 (but in the plots was used 1500x1500)

Is this fact known?