Speedbor bits or auger bits are fantastic and much better then spade bits. They have the little screw at the end that pulls the bit into and through the wood so you don't have to push hard on the drill.
I bought a IRWIN SPEEDBOR at Menards for $7.47, then I saw the entire package of Stubby Auger bits at Harbor Freight for $12.99 and an entire package of longer Auger bits for $16.99. I opened the Harbor Freight bits first with the plan to return the IRWIN bit if the Harbor Freight bits worked well. I was drilling 100 year old 2x4s and the Harbor Freight bits did not work well. The little screw kept becoming packed with wood(see the drill bit pictured below) and it wouldn't pull itself through the wood. I was cleaning it 2 or 3 times just to drill through 1 1/2 inches into a 2X4. I switched to the IRWIN bit and it has been FANTASTIC and worth the higher price. The screw on the end that pulls the bit into the wood did not jam or pack with sawdust even on the 100 year old wood. I did one more test with a Harbor Freight bit on newer recently purchased 2X4s and it worked fine and the screw didn't pack with sawdust. Do be careful as the bit drills fast and the torque will cause the drill to twist and can smash figures and twists wrists!