mörderisch
brutal
Colloquial and exaggerated for something that is extremely exhausting, difficult, or intense.
Wir mussten in einem mörderischen Tempo arbeiten, um die Frist einzuhalten.
We had to work at a brutal pace to meet the deadline.

murderous
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brutal
Colloquial and exaggerated for something that is extremely exhausting, difficult, or intense.
Wir mussten in einem mörderischen Tempo arbeiten, um die Frist einzuhalten.
We had to work at a brutal pace to meet the deadline.

The adjective 'mörderisch' (murderous) is derived from 'der Mord' (murder). The extreme and negative intensity of the word 'Mord' (murder) is transferred to the colloquial meanings in order to describe something as extremely exhausting or intense.
Wir hatten einen mörderischen Streit, aber jetzt ist alles wieder gut.
We had a terrible argument, but now everything is fine again.
You can recognize the literal meaning from contexts involving crime, police, or violence. The colloquial, exaggerated meanings refer to everyday things like pace, heat, noise, or exertion.
Die Polizei untersucht den mörderischen Angriff.
The police are investigating the murderous attack.
In the meaning 'extremely exhausting', 'mörderisch' (brutal) is often combined with nouns like 'Tempo' (pace), 'Wettbewerb' (competition), 'Stress' (stress), or 'Anstieg' (climb/increase).
Der mörderische Anstieg auf den Berg hat uns alle erschöpft.
The brutal climb up the mountain exhausted all of us.
As a colloquial intensifier, 'mörderisch' (terrible) describes an extreme, unpleasant state. Typical combinations are 'eine mörderische Hitze' (terrible heat), 'ein mörderischer Lärm' (terrible noise), or 'ein mörderischer Hunger' (terrible hunger).
Wegen des mörderischen Lärms der Baustelle konnte ich nicht schlafen.
Because of the terrible noise from the construction site, I couldn't sleep.
strong
'stark' and 'mörderisch' can both express high intensity. 'stark' is neutral and can be used very broadly, for example with 'starker Regen' (heavy rain), 'starke Schmerzen' (severe pain), or 'starker Stress' (high stress). 'mörderisch' is colloquial and deliberately exaggerated. It fits especially when something is extremely exhausting, intense, or unpleasant. Learners may confuse the words because both can mean 'very strong'. But 'mörderisch' sounds much more emotional and often negative; in factual situations, 'stark' is better.

Nach der Prüfung sagte Lena, dass der Zeitdruck mörderisch war.
After the exam, Lena said that the time pressure was brutal.
Am Nachmittag hat ein starker Wind die Fahrräder umgeworfen.
In the afternoon, a strong wind knocked over the bicycles.