Learn Italian: Pare che la latenza rovini la navigazione. - It seems that the latency ruins the navigation.

In the personal construction, the subject of the dependent clause (la latenza) becomes the subject of the main verb (parere), and the second verb changes to an infinitive. It would become: La latenza pare rovinare la navigazione.

Why is the verb rovini in the subjunctive mood here?

Impersonal expressions of appearance, opinion, or uncertainty, like pare che (it seems that) or sembra che, require the subjunctive in the dependent clause. Therefore, the regular present indicative rovina becomes the present subjunctive rovini.

Could I add an indirect object pronoun to specify who it seems that way to, like 'It seems to me that...'?

Yes, you can add an indirect object pronoun to make it Mi pare che la latenza rovini la navigazione. Adding this pronoun just clarifies whose opinion it is, but it doesn't change the grammar rules: expressions of personal opinion still require the subjunctive in the dependent clause.

Does navigazione just mean navigation like on a boat, or is there another meaning here?

While it traditionally means sailing or navigation, in modern Italian navigazione is the standard term for web browsing or surfing the internet. Alongside latenza (latency or lag), this sentence is discussing how a slow internet connection ruins the user experience.