I'm trying to do some clip process with a quile large layers but the process is too slow. When I see the task administrator, just around 28% of the CPU is being used. I've tried with 32-bit and 64-bit versions of QGIS 2.8 and 2.12. Same results: A clip of this layer takes hours, while ArcGIS 10.2 just needed 2 minutes. Does someone know what could be happening ??