In "pnmath_soln.R" script, I set,

v1 <- runif(1000)
v2 <- runif(100000000)
setNumPnmathThreads(2)

You can try same script by changing v1 and v2 to large sizes. Also "setNumPnmathThreads" to different number of threads(Suggestion try number of threads between 2 to 8).
 