A Perth judge has expressed concern at the length of time a 22-year-old woman could spend in custody before facing trial for allegedly murdering a teenage boy who was struck by a car at a bus stop.

Key points: Aya Hishmeh denies murdering one boy and attempting to kill four others in 2017

Aya Hishmeh denies murdering one boy and attempting to kill four others in 2017 She is in prison and her 20-day trial may not start until January next year

She is in prison and her 20-day trial may not start until January next year Another trial is needed in connection with an earlier incident at a fast food outlet

Aya Hishmeh, 22, is accused of running down and killing 17-year-old Jacob Cummins, who was among a group of teenagers who were hit by a car in Canning Vale in December 2017.

She is also accused of attempting to murder four of the other teenagers.

The alleged offences happened not long after a fight involving groups of youths at a nearby fast food restaurant.

Ms Hishmeh has pleaded not guilty to all the charges against her.

She has been in custody since her arrest on the day of the incident and today appeared briefly in the Supreme Court via video link from Bandyup Women's Prison.

Jacob Cummins died after he and a group of teenagers were hit by a car in Canning Vale. ( Supplied: Family )

Justice Michael Corboy said he was concerned about the time the case was taking, in particular suggestions that Ms Hismeh's 20-day trial would not start until either November this year or January next year.

Justice Corby said he was "unhappy" that the delay would mean Ms Hishmeh could end spending more than two years awaiting her trial.

'Considerable' evidence, prosecutor says

The state prosecutor said the case was taking some time, because there was a "considerable" amount of evidence and there had been "a lot of liaison" with major crash detectives.

The prosecutor said the trial dealing with charges from the earlier incident at the fast food outlet was due to take place in August, and many of the witnesses in that case were also witnesses in the murder trial.

A vigil was held for Jacob Cummins at Scarborough Beach after his death. ( ABC News: Emily Piesse )

She also said it was hoped the same state prosecutor would conduct both trials, and because of the unavailability of Mr Cummins's mother and a major crash expert, November this year seemed the appropriate date.

Defence barrister Tony Elliott, who asked for the trial to be "pencilled in" for January next year, said the defence team "was working on a solution" which might mean the trial could start earlier.

Justice Corboy ordered that the case come back to court at the end of the month to discuss the matter.

Ms Hishmeh was again remanded in custody.