Reactive time tests

How long does it take to call reactives and access reactiveValues?

library(shiny)
# Reactives with no changes (after first)
v <- reactiveValues(x = 0)
r0 <- reactive(1)           # 0 levels of dependence
r1 <- reactive(v$x)         # 1 level
r2 <- reactive(r1())        # 2 levels


# Reactives with change
vc <- reactiveValues(x = 0)
rc1 <- reactive(vc$x)
f_rc1 <- function() {
  vc$x <- vc$x + 1
  rc1()
}
rc2 <- reactive(rc1())
f_rc2 <- function() {
  vc$x <- vc$x + 1
  rc2()
}

library(microbenchmark)
isolate(microbenchmark(
  v$x,               # Use reactive value directly
  r0(),              # reactive with 0 levels
  r1(),              # reactive with 1 level
  r2(),              # reactive with 2 levels
  vc$x <- vc$x + 1,  # Change reactive value
  f_rc1(),           # Change reactive value, then call a dependent reactive (1 level)
  f_rc2()            # Change reactive value, then call a dependent reactive (2 levels)
))
## Unit: microseconds
##              expr    min     lq median     uq   max neval
##               v$x  228.4  239.3  246.0  254.9  1458   100
##              r0()  379.7  399.9  410.8  434.1  2573   100
##              r1()  381.5  398.2  411.9  424.5  3078   100
##              r2()  376.7  405.3  418.9  432.4  2763   100
##  vc$x <- vc$x + 1  640.1  686.4 1089.1 1593.1  2878   100
##           f_rc1() 2899.1 3118.6 3471.7 3947.4  9271   100
##           f_rc2() 4803.4 5158.6 5647.3 6112.7 44051   100

If the reactive has not been invalidated (there have been no changes to its ancestors in the reactive graph), it takes about 400us. If it has been invalidated, it takes about 2-3ms per level of reactivity.