விரைவானது is a correct word of "Fast" in this scenario. Because வேகமானது is a word of expressing fast in distance. But விரைவானது expressing the fast in the meaning of performances

Both are good. Let's wait for others suggestion too, moreover, most of the translators are giving suggestion for the first few words which are displayed at the begaining of https://translations.telegram.org/ta/ios/login/ and not having much interest in finding erroneous sentences. But, you're given good suggestions. Hence, we may change it when one more sincere user request the same.

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