Testing rails using capybara in drone is so slow

I have a problem here. so I found out that my rails app if tested locally in my laptop(OSX) it only need 10-15 minutes to finish. However, when I test it using drone it need about 2 hours. I checked it and found that capybara is the problem. when the test is using capybara it became very slow.

any body have an idea why is it happening?