If your mouse moves too slow after disabling mouse acceleration you can use the following script. It (ab)uses the 'simple' acceleration profile since the xinput constant deceleration setting cannot be used for values between 0 and 1.
device="Dell Dell USB Optical Mouse"
resolution_percent="241" # Greater than 100, use constant deceleration otherwise with profile -1.
xinput set-prop "$device" "Device Accel Profile" 4 # Simple profile with threshold 0 allows constant scaling up
xinput set-ptr-feedback "$device" 0 "$resolution_percent" 100 # Set threshold to 0 and acceleration to $resolution_percent/100
You'll have to modify the script by using your particular device name. You can look that up by running xinput without arguments. Also the script has to be run each time the mouse is connected or when you start the system.