More specifically, you would do yourself a disservice to not read and understand the manual regarding warping. To simply say turn warping off will leave you frustrated wondering why people use Live in the first place. It may not be intuitive at first, but once you understand how to control warping, and learn why it sounds like that when using the current warp settings, you will unlock a big part of the program. Essentially, plan on warping any audio longer than a one shot. That doesn't automatically mean you intend to mangle it, loop it, etc... It's just how Live handles audio. Knowing the best way to tackle the type of audio you are working with will make a huge difference in your perception of Live.
In short, turning off warping will make it difficult to continue working on your project. When warping is on, you must consider the tempo of the set, and audio clip. You can even set the tempo master to that audio clip if you must. Your chugging is happening because Live made some decisions about the tempo of your audio that are not correct, and is stretching your audio drastically, causing the awkward artifacts. Correctly setting warp markers, and setting the sets tempo accordingly will fix this issue. It might be worth looking at other warp modes than the default "beats". This is the preferred warp algorithm for percussion with sharp transients and decay, but not do much tonal content such as your piano.
Tim Tilberg - Duluth, MN | SoundCloud - Arsenal
2011 13" MBP w/8GB ram | Live 9 Suite, Reason 6.5, FXPansion DCAM/Etch/Maul, Izotope Ozone 5