When CPU at 100%, loss of ocl performance ?

[Mem5]

oclhashcat command line is already with -a (I do a digits only bruteforce on WPA) so no dictonnary needed).
With ocl-plus 0.15 it works ok but not anymore with v1.00.
Graphic card : MSI R7970 Twin Frozr 3GD5/OC BE 3 Go
Driver : 13-9_win7_win8_64_dd_ccc_whql