In order to continuously monitor the performance of gtable the following piece of code is used to generate a profile and inspect it:

library(ggplot2)
library(profvis)

p <- ggplot(mtcars, aes(mpg, disp)) + 
  geom_point() + 
  facet_grid(gear~cyl)

p_build <- ggplot_build(p)

profile <- profvis(for (i in seq_len(100)) ggplot_gtable(p_build))

profile