[quote user="Gili Zafrani"]what do you mean "words" ? the global \static variables, ?[/quote]
One word is two bytes. It is the native data size of the MSP CPU. It can read or write a word with one instruction.
The more initialized (or implicitly initialized) data/variables you have, the more clock cycles does the MSP need to copy over the init values (or set these variables to zero).
Declare all constant data as CONST, so it stays in FLASH and doesn't have to be initialized (saves ram too) and put all global or static arrays/buffers that don't need initialization into the no_init section.