Learn Hardcore Portuguese (Portugal): Quando o sistema ficar lento, reinicia-o. - When the system becomes slow, restart it.

The clause introduced by quando refers to a future event. In Portuguese, after conjunctions like quando, assim que, logo que, etc., you use the future subjunctive to talk about something that may happen. Here, ficar is the future subjunctive form of ficar, matching the infinitive form.

How is the future subjunctive of ficar formed?

You start from the third-person plural preterite ficaram, drop -ram to get the stem fica-, and then add the future-subjunctive endings. In the singular third person, the ending coincides with the infinitive, so you get ficar.

Why is the command reinicia used instead of reinicie or reiniciar?

reinicia is the affirmative imperative for tu (second-person singular) of the verb reiniciar. For -ar verbs, the tu imperative is formed by taking the present indicative reinicias and dropping the final -s, giving reinicia.

Why does the sentence appear as reinicia-o with a hyphen, instead of just reinicia?

In an affirmative imperative, if you want to include the direct-object pronoun meaning “it,” you must attach it after the verb (this is called enclisis) and link them with a hyphen. So reinicia-o literally means “restart it.” Simply writing reinicia would leave out the object.

Why is the pronoun written as o and not lo?

In modern European Portuguese, the third-person masculine singular direct-object pronoun is o. Unlike Spanish, Portuguese does not use lo. You keep the form -o and attach it with a hyphen.

Could I instead write Reinicia o sistema quando ficar lento, and how does that affect pronoun usage?

Yes. You can spell out the noun instead of using the pronoun: Reinicia o sistema quando ficar lento. In this version, there’s no clitic pronoun, so no hyphen is needed. The word order is also flexible: you could put the subordinate clause first or second without changing the meaning.

Is it possible to use quando o sistema fica lento instead of ficar lento?

In everyday speech—especially in Brazilian Portuguese—people often use the present indicative fica (“when the system gets slow”). However, in formal European Portuguese and in technical instructions, the future subjunctive (ficar) is preferred after quando to emphasize that you’re talking about a possible future event.

What is the difference between ficar lento and estar lento?

ficar highlights a change of state (“to become/get slow”), whereas estar simply describes a state (“to be slow”). Using ficar lento implies the system transitions into that slow condition.

How would I change reinicia-o if I wanted to use the formal você rather than tu?

You’d use the formal imperative form reinicie. To include the pronoun, attach it with a hyphen: reinicie-o (“please restart it,” formal you).