App.open() long resolve time

I just tested on Windows 10 with Java 11 on SikuliX 1.1.4:

start = time.time()
paintpath = r'c:\WINDOWS\system32\mspaint.exe'
paint = App(paintpath) # will not open the app, but detect if already open
print paint
paint.open() # this opens the app or uses already open app
print paint
print "Duration:", time.time() - start

you should read:
https://sikulix-2014.readthedocs.io/en/latest/appclass.html

I guess you are running the script from commandline.
If starting the app as a first action, you have to take into account the start-up time of about 3 - 5 seconds.

Look here for options how to run scripts from a masterscript, which would avoid the startup for the second and all other scripts.
https://sikulix-2014.readthedocs.io/en/latest/scripting.html#running-scripts-and-snippets-from-within-other-scripts-and-run-scripts-one-after-the-other

There are some other options how to organize your stuff, so that you avoid the startup delay.

another script, that actively detects an already opened app

start = time.time()
paintpath = r'c:\WINDOWS\system32\mspaint.exe'
paint = App(paintpath)
if not paint.isRunning(0):
    print "not running"
    paint.open()
else:
    print "already running"
print paint
print "Duration:", time.time() - start

… forgot to mention, that the SikuliX overhead to open/focus/close an app is at about 0.5 seconds on average.