How to remove Adafruit Pro Trinket bootloader flashing startup sequence From what I understand, the Pro Trinket has "Optiboot" which allows it to detect which boot loader you are trying to use, one for USB and one for FTDI. When it's in this "bootloader state" the red LED on pin 13 buses for 10 seconds before it starts to run the program I've programmed. 

Can I remove this Optiboot functionality? Would that entail permanently choosing a single boot loader/interface?

One problem I have with this is that along with the LED on 13, it causes the LED strip I have attached to pins 9, 10, 11 to blink. I would also really like to not have to wait 10 seconds to start running code.

Here's the page on Adafruit's site that talks about the bootloader[s] on the Pro Trinket.

Thanks!
You could take the Pro Trinket bootloader source code and tweak it to your needs, burn it, and make sure you have patience and debugging skills.

From the author's (Frank Zhao) source code, it seems that this is the 10 seconds loop you are referring to, located in main.c, line #456:

if ( ((usbHasRxed != 0) &amp;&amp; (timeout &gt; USBBOOTLOADER_TIMEOUT)


The USBBOOTLOADER_TIMEOUT variable which is defined to 10 at the top of that file, line #70:

#define USBBOOTLOADER_TIMEOUT 10


and is progressed after 'roughly' 1 second, at line #496:

// roughly 1 second
#if (F_CPU == 12000000)
    if (t1ovf &gt; 183) {
    #elif (F_CPU == 16000000)
    if (t1ovf &gt; 244) {
    #endif
        t1ovf = 0;
        timeout++;
    }