I had some issue with old profile so made a new profile (dsbros).
@weldsmith I am using TMC2100 driver.
How are you measuring the speed to verify that it is not going as fast and is it drastically slower when using acceleration?
-I don't have any tool but Visually you can make out the difference is high.
OK,
Post your latest code with your slower speeds and accel rate.
Dave
// ConstantSpeed.pde
// -*- mode: C++ -*-
//
// Shows how to run AccelStepper in the simplest,
// fixed speed mode with no accelerations
/// \author Mike McCauley (mikem@airspayce.com)
// Copyright (C) 2009 Mike McCauley
// $Id: ConstantSpeed.pde,v 1.1 2011/01/05 01:51:01 mikem Exp mikem $
#include <AccelStepper.h>
AccelStepper stepper(1, 12, 13);
void setup()
{
stepper.setMaxSpeed(5500);
stepper.setSpeed(3500);
stepper.setAcceleration(4000); // I tired greater value also, any value greater than 3500 speed is //constant
pinMode(16, OUTPUT);
digitalWrite(16,LOW);
}
void loop()
{
// If at the end of travel go to the other end
if (stepper.distanceToGo() == 0)
stepper.moveTo(-stepper.currentPosition());
stepper.run();
}
I just got back from vacation and saw your reply. Your code does not make a lot of sense. I am interested in how far you are rotating the Motor.
Dave.
How was your vacation?
Same here 
I was on vacation.
Do you mean maximum distance to which motor will travel?
I am looking for how many degrees of rotation.