VBScript performance tip

[rray]

or rather a "warning" for everyone using VBScript

using local object variables in vbscript subs and functions is extremely slow when not using dim!

compare...

Code: Select all

start_t = timer
for n = 0 to 1000
	Set s = getvar()
next
logmessage("time=" & 1000*(timer-start_t) & " milliseconds")

function getvar()
	Set i = Application.Selection
	Set getvar = i
end function

[/size]

outputs

time=492,1875 milliseconds

while

Code: Select all

start_t = timer
for n = 0 to 1000
	Set s = getvar()
next
logmessage("time=" & 1000*(timer-start_t) & " milliseconds")

function getvar()
	Dim i
	Set i = Application.Selection
	Set getvar = i
end function

[/size]

outputs

time=3,90625 milliseconds

only difference is the "Dim i" !

It's probably a good idea to use "option explicit" at the top of the script so you're forced to declare everything