It is noted that, "80 chars. sent over a duration of 3,500µS", works out to just under 44µS/char. (which IS "reasonable.") Using a (likely) newer, contrast enhanced, 4x20 display - we achieved similar "screen fills" in ~3,200µS - simply via an 8 bit parallel bus. (no use of EPI) Note that, "issuing a display clear" (code 0x01) causes a "long delay" - yet if the "entire screen is rewritten" - there is no need for such "clear display." Much depends upon, "What, Where & Length" of New Data. Screen "Write-Times" can be substantially reduced if only 20-30 char. positions are to be "over-written." A final caution - "over-writing existing data - especially when, "No change is indicated/required" - may yield a noticeable "flicker" - and may even produce a "beat-frequency" with a "PWM" modulated backlight. Selective display update (rather than blind update) proves optimal...
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