Variable names exist more as a programmer aide - when a program or script is interpreted, these are converted into memory locations. Shorter variables will only negatively impact performance of the programmer(s) when modifying / debugging code in the future.
Obfuscation is a widely used technique that involves replacing variable names with single/multi-character variable names, but that is used in an attempt to make reverse engineering / lifting core technology from projects where the source code is readily available / easily extracted more difficult.