Instead of using one 100ft ethernet cable, I want to use two 50ft cables and use an ethernet extender. Will I experience any lag or loss in transmission due to the extender? if so, why would that be?
100ft is only 1/3 of the max length for an ethernet cable. That should work with two 50ft. Make sure the cables and the plugs are in good condition. The general problem with extenders is, that the contacts work as a resistor and a capacitor and change the parameter of the cable.
It depends what you mean "extender". A electronic device would work it is basically just a switch and if you get extremely technical is does delay the traffic some fraction of 1ms. Now if what you are calling a extender are those little plastic device with a RJ45 on each side that you can buy for a couple dollars those are normally called couplers. At the distance you are looking at there is no issue. I am sure they could cause a issue if you were near the 100m limit but it is hard to predict how much.
In my opinion you don't need any Ethernet extender because Cat-5 cable works fine up to 500 ft. So you can use the 100 ft cable as it is and no amplifiers required plus you will the good packet delivery and quality as well.
This is completely and totally false. Don't go around finding old thread and putting in invalid updates. Cat5 cable will not work up to 500ft for ethernet it is limited to 100m.