Speed makes people very boring and uncreative.
This is not necessarily true at all. Perhaps extremely high doses lead to stereotypic thought patterns and motor behavior, but moderate doses don't have that same effect. I have taken therapeutic-level doses of dextroamphetamine for years and years and it has not, in any way, turned me into some sort of boring, mindless automaton. It has, however, greatly helped my life, having fantastic anxiolytic effects and cutting through an almost dissociative 'brain fog.'
If anyone is interested, there is a preliminary peer-reviewed study regarding amphetamines and creativity (mind you it is hard to measure creativity empirically):
Farah MJ, Haimm C, Sankoorikal G and Chatterjee A (2008). When we enhance cognition with Adderall, do we sacrifice creativity? A preliminary study.
Psychopharmacology. Adv. Online Pub: 10.1007/s00213-008-1369-3.
The authors found that, no, we don't necessarily sacrifice creativity: "Nevertheless, the findings of reliable enhancement effects of Adderall in one task and ability-dependent effects in another task tell us that the answer to the title question is not a simple “yes”. The neuroethical worry that widespread stimulant use could create a general downward shift in the creativity of the population is assuaged by the present results."
But this has greatly veered off the original topic.