Si el navegador va lento, prefiero reiniciar el portátil.

Yes, in this sentence si means if and introduces a condition: Si el navegador va lento... = If the browser is slow...

A very important warning for English speakers:

• si = if
• sí = yes

The written accent matters. In this sentence there is no accent, so it is the conditional word if.

Ir is often used in Spanish to talk about how something is functioning or performing, especially machines, software, internet, traffic, and processes.

So:

• El navegador va lento = The browser is running slowly / is slow
• literally, the browser goes slow

This is very natural Spanish. A few similar examples:

• Mi ordenador va muy bien. = My computer runs very well.
• Internet va fatal. = The internet is working terribly.
• El coche ya no va bien. = The car no longer runs well.

You may also hear está lento in some varieties of Spanish, but va lento sounds very natural here, especially when talking about performance.

After ir, Spanish often uses an adjective, not an adverb, to describe how something functions.

So Spanish says:

• va lento
• va rápido
• va bien
• va mal

Even though English would often use an adverb, Spanish does not always match that pattern directly.

So va lento is the normal, natural way to say that the browser is slow.

Spanish uses definite articles much more often than English.

Here:

• el navegador = the browser
• el portátil = the laptop

Even when English might sometimes sound more general, Spanish often still uses el / la / los / las.

In this sentence, the speaker is probably talking about:

• the browser they are using
• the laptop they are using

So the article sounds completely normal.

Here navegador means browser, as in an internet browser like Chrome, Firefox, Safari, or Edge.

It can also mean navigator in other contexts, but in computer-related sentences like this one, navegador normally means web browser.

So:

• el navegador = the browser
• navegador web = web browser

Spanish usually drops subject pronouns when they are not needed, because the verb ending already shows who the subject is.

• prefiero = I prefer

The -o ending tells you it is I.

So prefiero is normally enough. You could say yo prefiero, but that would usually add emphasis or contrast, for example:

• Yo prefiero reiniciar el portátil, pero ella prefiere cerrar el navegador. = I prefer to restart the laptop, but she prefers to close the browser.

In a neutral sentence, prefiero alone is more natural.

Because preferir is a stem-changing verb in the present tense.

The e in the stem changes to ie in many forms:

• yo prefiero
• tú prefieres
• él/ella prefiere
• nosotros preferimos
• vosotros preferís
• ellos prefieren

Notice that nosotros and vosotros do not have the stem change.

So prefiero is the normal I form of preferir.

After preferir, Spanish normally uses a bare infinitive directly.

So:

• Prefiero reiniciar el portátil. = I prefer to restart the laptop.

No extra preposition is needed.

This is similar to:

• Quiero comer. = I want to eat.
• Necesito descansar. = I need to rest.
• Prefiero esperar. = I prefer to wait.

However, if you compare one action with another, you can also say:

• Prefiero reiniciar el portátil antes que seguir esperando. = I prefer to restart the laptop rather than keep waiting.

In this sentence, reiniciar means to restart / reboot a device.

• reiniciar el portátil = to restart the laptop

You do not need de nuevo, because re- already contains the idea of doing something again. So reiniciar de nuevo would usually sound repetitive.

As for reiniciarse, that is the reflexive form and is used when something restarts itself:

• El portátil se reinició solo. = The laptop restarted itself.

But when a person restarts the device, Spanish normally uses the non-reflexive form:

• Reinicié el portátil. = I restarted the laptop.

Yes. In Spain, portátil is a very common word for laptop.

So:

• el portátil = the laptop

You may also hear:

• ordenador portátil = laptop computer

In much of Latin America, people more often say:

• la laptop
• la computadora portátil

So el portátil is a very Spain-oriented choice, which matches your target variety.

Yes, it could be reversed.

The sentence as written starts with the condition:

• Si el navegador va lento, prefiero reiniciar el portátil.

This is very natural and highlights the situation first.

You could also say:

• Prefiero reiniciar el portátil si el navegador va lento.

That also works. The meaning is basically the same, though the focus shifts slightly toward the preference first.

When the si clause comes first, Spanish normally puts a comma after it, as in the original sentence.

Here the present tense is completely normal because the sentence expresses a real or likely condition in the present.

Pattern:

• Si + present, present
• Si + present, future
• Si + present, imperative

In this sentence:

• Si el navegador va lento = if the browser is slow
• prefiero reiniciar el portátil = I prefer to restart the laptop

This is a general, real-world statement about what the speaker usually prefers in that situation.

For example:

• Si tengo tiempo, voy. = If I have time, I go / I’ll go.
• Si hace frío, cierro la ventana. = If it’s cold, I close the window.

So the present tense in both parts is correct and natural.

Sometimes, but the meaning changes.

• si = if
• cuando = when

So:

• Si el navegador va lento... means the speaker is talking about a possible condition.
• Cuando el navegador va lento... suggests that this is something that happens, and whenever it happens, the speaker reacts that way.

Compare:

• Si el navegador va lento, prefiero reiniciar el portátil. = If the browser is slow, I prefer to restart the laptop.

• Cuando el navegador va lento, prefiero reiniciar el portátil. = When the browser is slow, I prefer to restart the laptop.

Both can be grammatical, but they are not exactly the same in meaning.

Normally reiniciar means restart / reboot, not shut down completely.

So the usual interpretation is:

• the laptop is already on
• you restart it

If you want to say turn off, you would usually say:

• apagar el portátil = turn off the laptop

If you want turn on, then:

• encender el portátil = turn on the laptop

So reiniciar is specifically restart in normal computer usage.

Yes, it sounds natural.

A speaker in Spain would easily understand and use:

• navegador
• va lento
• prefiero
• reiniciar
• el portátil

If you want a slightly more conversational version, someone might also say:

• Si el navegador va muy lento, prefiero reiniciar el portátil.
• Si el navegador se queda pillado, prefiero reiniciar el portátil.

But the original sentence is already clear and natural.