In order to continuously monitor the performance of ggplot2 the following piece of code is used to generate a profile and inspect it:
library(ggplot2)
library(profvis)
p <- ggplot(mtcars, aes(x = mpg, y = disp)) +
geom_point() +
facet_grid(gear ~ cyl)
profile <- profvis(for (i in seq_len(100)) ggplotGrob(p))
profile