Is the word lento the same in Brazilian and European Portuguese?

Yes

The meaning, spelling, and grammar of the word "lento" are identical in both Brazilian and Continental Portuguese. The only differences are phonetic. Brazilian Portuguese tends to have more open vowels and a more melodic, syllable-timed rhythm. In contrast, Continental Portuguese is characterized by significant vowel reduction, where unstressed vowels (like the "o" in "lento") are pronounced much more closed or even nearly silenced, giving the language a more stress-timed sound.

Brazilian Portuguese

1. A internet está muito lenta hoje. (The internet is very slow today.)
2. Ele é um pouco lento para aprender. (He is a bit slow to learn.)
3. O ritmo da música é muito lento. (The rhythm of the music is very slow.)
4. O crescimento da planta está lento. (The plant's growth is slow.)
5. O trânsito está lento por causa da chuva. (Traffic is slow because of the rain.)

Continental Portuguese

1. A internet está muito lenta hoje. (The internet is very slow today.)
2. Ele é um pouco lento a aprender. (He is a bit slow to learn.)
3. O ritmo da música é muito lento. (The rhythm of the music is very slow.)
4. O crescimento da planta está lento. (The plant's growth is slow.)
5. O trânsito está lento por causa da chuva. (Traffic is slow because of the rain.)