Playing passages of descending slurred semiquavers (sixteenth-notes) with even rhythm and clear articulation presents a challenge. This is especially so when the passage includes string crossing.
Focusing on the left hand will help. Finger the notes without using the bow, lifting the fingers with energy and preparing fingers in time.
Also practise with separate bows (détaché, martelé or collé), adding extra notes of the same pitch on long notes, as shown in the score.
Our ears can gloss over weak coordination when listening to slurs; you will hear any problems more easily when playing with separate bows.
This is the opening of the 1st movement of Beethoven's "Spring Sonata".
Scores - Beethoven Spring Sonata Excerpt - violin & viola