the build i been using is scythe => upgrade machete fully (doing even upgrades) => auto machete => saw => upgrade saw starting with cheapest. and getting axe either before auto or before saw.
i noticed the saw taking only 3 seconds. i was amazed and counted off the time. i thought i didnt upgrade it but maybe i did. i started over and tried to recreate and couldnt with saw at max speed, tho i noticed scythe only taking 1.5 seconds and i didnt upgrade speed (it said 100 to upg). i sense its the auto causing a bug or just speeding everything up except the machete seems to be on time with 2 hits per second.