If you've upgraded to 2.1 and are finding the flash usage is too high for your project, then there's a simple fix available from the code generator for LCD screens, choose "Uno - Low memory" in the properties.

Likewise, for AVR the SSD1306Ascii driver uses less memory at the expense of a bit of lost functonality.

Using either LCD in Uno mode, or the SSD1306Ascii plugin should result in very similar memory requirements to 1.7.