I use the Atollic Truestudio (STM32F) and Code Red (LPC1xxx) tool-chains which are based on the Eclipse IDE and speed is a non-issue. Personally I regard them as significantly faster and much more pleasant to work with than MPLAB (I have not yet tried X). The plug-ins available from Atollic, such as TrueINSPECTOR (static source code inspection, MISRA-C), TrueANALYZER (code coverage analysis) and TrueVERIFIER (advanced test automation) are really useful for developing, testing and maintaining complex embedded systems.