pushing it
If he has to push it to get it through the wood he needs you to touch up the chain. Aside from that, a lot of saw owners never learn how to use a saw properly. They never catch on that a light touch (saw's rpms stays in the power band) cuts faster than a heavy push (nearly stalls the saw from trying to grab too much at once). You can hand them a brand new power ported saw and they still push/lean into it like they they were using their old saw with a dull chain. Their time through a cut is twice what yours is even with your saw in their hands. It's all in how you handle the saw, your style of cutting. It's very difficult to get them to break their old habits and lighten up when they cut. Their sweating just from the pushing they put on the saw. I still get a laugh out of the time I handed Bob my ported saw to let him try a cut or two with it. He steps up to the tree like he always does and goes to make his notch. He did heed my words on starting the chain moving before you touch wood. He then leans on the saw just like he had his own saw in his hands. Zip, in the blink of an eye he pushed the saw clear through the tree and he's standing there with this look of horror in his face, he doesn't know which way to run. The saw went cleanly through the tree and it's standing on the stump. Luckily the tree fell away from him but for a momnent there you could hear him load his pants trying to decide which way to run. Or the guy next door, driving me crazy with fifteen minutes of revs up and down, trying to saw through his Yews to remove them and just making smoke. I went out and told him to just give me the saw for a few miniutes and I'd sharpen it for him. Ten miniutes later I hand him the saw back and he goes for Yew bushes again. This time, he leans into it with all his weight, just like he was before the quick touch up on the chain. The saw rips through about 15 branches (1" branches) and he goes ass over tin cups into the yard. The saw is buried full bar into the dirt and he's laying flat on his back after taking a flip into the yard as he was burying the saw into the dirt. It takes a light touch, NOT a heavy push!
A quick touch up after every tank of fuel will let your saw and chain last longer and it's a good thing. Burning your way through the wood with a heavy push is not. Short of racing where you're trying to knock a hundreth of a second off your cut time you DO NOT need to push/lean into the saw to cut well with it, nine times out of ten the chain needs a quick touch up. One other one comes to mind and I got it on film. The guy, with his little red Craftsman saw trying to down a cherry tree that had dropped a limb through the windshield of his wife's car. Smoke going everywhere and the saw going nowhere. After he went through 2 tanks of gas, and was on the way through his third, I asked him to take a break and I'd file the chain for him. The first two tanks got the notch done but the back cut wasn't happening. He was straining to get the saw through the backcut and it would not go. His style of cutting was push for all your worth and it'll go over. The saw was wheezing from the load on it. A good filing while he takes a break and back to the tree he goes. 20 seconds later the tree goes over. Sharpen the chain for your Father-in-law and good luck trying to get him to change his cutting style. I don't see it happening. He may not be able to change at this late date, bad habit used too long is very tough to break.The people depicted in these stories are real and any resemblance to homeowners is intentional. They are all characters in their own right but need help with their cutting style ( push for all you're worth) and chain sharpening technique (It ain't dull yet, See it's still cutting, difficult to see through the smoke though).