Reddit reviews Shimano Road Acer Cable and sleeve Black 2016

7900/6700/5700 have notoriously poor shifting, but it can be improved with some tricks. Once you follow all the other advice here (make sure your hanger is straight, etc.), then I suggest you take a look at the cables and housing.

When this series was new, Shimano specced a PTFE-coated shift cable and housing which was included only one nylon ferrule, while the rest were CNCed aluminum. This was designed to aid in the shifting by reducing the friction from the lever and stiffening the shifts at the frame, but even this didn't help too much. After 9000 came out, and Shimano introduced their polymer cables (Shimano SP41 housing didn't change), I began putting these new cables on the previous generation of Shimano shifters, and I found this and a very clean routing of the housing (often crossing them in front of the headtube, so that the cables crossed again on the downtube) made a huge difference, that often means this generation of Shimano can shift beautifully.

tl;dr - Use slick cables, and good housing with very clean bends. Shimano has trickled it all the way down the line to budget Optislik Cables, while other manufacturers like Jagwire responded with their own Teflon cables, and now their new high-polish stainless steel cable (which which I have no experience).