You can make the display slightly faster.  It uses software SPI.  For Marlin 1.1.x, the timing values are defined in Conditionals_LCD.h

#elif ENABLED(CR10_STOCKDISPLAY)

  #define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
  #ifndef ST7920_DELAY_1
//    #define ST7920_DELAY_1 DELAY_NS(125)
    #define ST7920_DELAY_1 DELAY_NS(64)
  #endif
  #ifndef ST7920_DELAY_2
//    #define ST7920_DELAY_2 DELAY_NS(125)
    #define ST7920_DELAY_2 DELAY_NS(64)
  #endif
  #ifndef ST7920_DELAY_3
//    #define ST7920_DELAY_3 DELAY_NS(125)
    #define ST7920_DELAY_3 DELAY_NS(64)
  #endif

#elif ENABLED(MKS_12864OLED)

The lion kingdom managed to get them down to 64, but no lower.  

More SPI delays are defined in ultralcd_st7920_u8glib_rrd.h

ST7920_WRITE_BYTE, ST7920_WRITE_BYTES, ST7920_SET_CMD, ST7920_SET_DAT, ST7920_CS

all have delays but the lion kingdom didn't have any luck reducing those.