Thanks to vincent to report this information. On a MacBook Pro Core iX, both USB port do NOT deliver the same performance level. To illustrate the difference, hereafter are captures of a test performed with a SSD drive installed in an external enclosure USB 2.0:
On the USB port located close to the user sitting in front of his MBP, the following results are obtained:
On the most distant USB port from the user:
The first port is almost twice slower than the second one, limited to 15 MB/s in writing and 22 MB/s in reading, while the other port reaches the maximal performance level offered by the USB 2.0 enclosure.
We tried to understand the reason behind such difference:
On the left panel the information for the slow USB port, and on the right panel the port for the faster port. The slow port is shared with the SD card slot as well as the Bluetooth controller and the keyboard and the trackpad, while the faster USB port is only shared with the iSight and the IR. This is rather a pity as Apple could have created several independent lines from the chipset, instead of putting several units in series on the same line...