The SPF, representing rank and file officers, criticised “farcical levels of disturbance and inconvenience”, with courts facing an “unrealistic” volume of cases.
It said it appeared the Crown Office and Procurator Fiscal Service (COPFS) was “overwhelmed”.
Holyrood’s Justice Committee is carrying out an inquiry into the role of COPFS and will hear from Calum Steele, SPF general secretary, on Tuesday.
In a submission to the committee, he praised the “dedicated, professional and incredibly hard-working” staff working in the prosecution service.
But he added: “It is the experience of our members that when matters get to court, the procurators fiscal are often unprepared and lack knowledge of the case”.
The SPF said engagement with prosecutors on complex and serious cases was usually “second to none” but raised concerns that the COPFS “does not have the skill set to carry out its role effectively” in cases involving new technologies.
Steele’s submission states: “The SPF believes that the COPFS needs to significantly ‘up its game’ in both its dealing with victims and witnesses.
“This is especially true when it comes to the court experience where what can only be described as farcical levels of disturbance and inconvenience are experienced.
“We appreciate that court scheduling is a matter not directly in the hands of the COPFS but the volume of cases that can be laid down for a particular court hearing are by any measure unrealistic.”
The federation said too many cases were being adjourned or abandoned.
“In many cases victims lose confidence in the justice system and witnesses are increasingly frustrated at having to waste their days lolling around court corridors.”