Learn English – the meaning of “slow time”

This sentence is about social movements, associations of people with a common goal (probably political). A movement is slow-building if it starts with few people and little media recognition, and progressively becomes better known. The movement builds up slowly over time, as it gathers more participants and organizes more activities. Slow-building implies that the movement was built slowly, as a result of a sustained effort or a passive rise towards success, and that this building up is still ongoing.

"Sufficient" means "enough", "an adequate amount". So "sufficient time" means the amount of time you need to get a certain job or task done. "Given sufficient time" is a fairly common phrase used when you want to say that something may be difficult, but if the person attempting the task is allowed to work on it for long enough they should be able to succeed. Like, "I don't know the answer to that question, but given sufficient time I could look it up." Or, "We can't get that done today, but given sufficient time -- probably about a week -- we could complete that for you."

"Overtime" is a little different. "Overtime" is used in sports to mean that a game is allowed to go beyond the usual time limits, usually because there is a tie score and so we keep playing until one team or the other scores and can be declared the winner. In business, "overtime" means hours worked over your regular hours, usually 40 hours per week. In the U.S., at least, many workers are paid 150% of their normal hourly wages for each hour of overtime.

"In the long run" is a phrase used to distinguish the long-term effect of something from short-term effects. Like, "Dieting and exercise may seem painful now, but in the long run you will be healthier if you keep it up." Or, "In the short term the stock market has many ups and down, but in the long run it always go up." It is often used to express the inevitably of some final outcome, like JK Galbraith's famous retort to criticisms of the long term effects of his ideas: "In the long run, we are all dead."