It was on the default so I guess 200ms. I changed it to 70ms and I have the feeling it’s running smoother already 
About the issue discussed above, I really have the feeling I did not have this issue before I introduced the inter-note rests…
Could you check if I am doing something obviously wrong in the updated loop?
// can't just Pseq because we need to account for insertions
this.pattern = Prout { |inval|
//Starting variables
var item, node,
clock = TempoClock,
barline = clock.nextBar,
nextTime, delta, restTime, endTime;
baseBarBeat = barline;
//start with the first node in the sequence
node = sequence.nodeAt(0);
while {
//While we have items in the sequence do this loop (infinite)
item = node.tryPerform(\obj);
item.notNil
} {
//Our next event's start-time
nextTime = barline + item[\time];
//if this is bigger then current beats this means we are in the start of our loop ->
//so we yield silence till the first event starts
if(clock.beats < nextTime) {
inval = Event.silent(nextTime - clock.beats).yield;
};
// now we arrived at the event
//calculate the end time of the event
endTime = item[\time] + item[\sustain];
// calculate the "rest" time after this node.
// if it's last in sequence we substract it with the 'next-bar' time a.k.a. sequence length
if(node.next.notNil) {
restTime = node.next.obj[\time] - endTime;
delta = node.next.obj[\time] - item[\time]; //used for next-barline calculation
} {
restTime = patternDur - endTime;
delta = patternDur - item[\time]; //used for next-barline calculation
};
//we need to update the 'next-bar' variable once we will reach the end of the current bar-sequence
if(clock.beats + delta - barline >= patternDur) {
barline = barline + patternDur;
baseBarBeat = barline;
};
//we prepare our Event
if( midiOut.notNil, {
inval = item.copy.put(\type, \midi).put(\midiout, midiOut).put(\channel, 1).put(\midinote, 0);
},{
inval = item.copy.put(\type, \note).put(\instrument, synthDef).put(\note, 0);
});
//whenever there is a crossover with notes (multi-voiced) we need to calculate the duration and legato
if( node.next.notNil and: { node.next.obj[\time] < endTime } , {
var dur, legato;
dur = node.next.obj[\time] - item[\time];
legato = item[\sustain] / dur;
//simply play the note until start of the next note - the legato will take care of the crossover part
inval = inval.copy.put(\dur, dur).put(\legato, legato).yield;
}, {
//smoothly lined up with rests so we simply take the note's duration as \dur argument
inval = inval.copy.put(\dur, item[\sustain]).yield;
//we also need to play the silent event after the note is finished until reaching to the next one
inval = Event.silent( restTime ).yield;
});
//continue the loop
node = node.next;
if(node.isNil) { node = sequence.nodeAt(0) };
}
};
this.stream = pattern.asStream;
Thnx a million!