precedence of setInterval, eval and print execution

Thanks for the responses. I'll definitely look into the output buffer limitations. How can I find out about the size?
The device is an Espruino WiFi on 1.99.
Here is the part of the code that matters:

  // measures and counts, counter reset ff below threshold
  meas() {
    const v = Math.round(analogRead(this.pin) * this.rng - this.offs)
    if (this.vals.length === this.nmax) this.vals.shift()
    this.vals.push(v)
    if (this.both === true) v = Math.abs(v)  // zero based, both too low and too high considered
    if (v < this.thr) {
      return this.cnt = 0
    } else {
      if (++this.cnt > this.tcnt) this.cnt = this.tcnt
      return this.cnt
    }
  }

  // call meas, evaluate and call back
  cfrm() {
    const c = this.meas()
    if (c === 0) return this.cb(this.val = 0)
    if (c === this.tcnt) return this.cb(this.val = 1)
    if (this.tcfm === 0) {
      // this.cb(this.val = 0)  // not yet confirmed, do nothing (?)
    } else {
      setTimeout(this.meas.bind(this), this.tcfm)
    }
  }

  start(cb) {
    if (cb === undefined) cb = this.cb || print
    this.cb = cb
    this.iv = setInterval(this.cfrm.bind(this), this.tupd)
    this.cfrm()
  }

There are 2 sensor instances running, one with an interval (this.tupd) of 400 ms, the other one 2 s.
'this.cb' is a callback to little instance that keeps track of the 0/1 values sent and eventually switches a light through a MOSFET, along with a TPC notification to the controlling server:

  // called by switching (presence) sensor
  cbsnsr(v) {
    this.snsr = v  // just for information
    if (this.ovrd === 1 || this.toff !== undefined) return
    // act if all conditions are met
    if (v === 1 && this.enbl === 1) this.act()
  }

  act() {
    this.tend = Date.now() + this.drtn      // just for information
    if (this.toon) clearTimeout(this.toon)  // to re-set timeout while already running
    const self = this
    this.toon = setTimeout(function() {
      self.toon = undefined
      // if (self.toff) clearTimeout(self.toff)
      // self.toff = setTimeout(function() {self.toff = undefined}, self.dblk)
      self.actr(0)
    }, this.drtn)
    if (this.val !== 1) this.actr(1) // switch on
  }

  actr(v) {
    digitalWrite(this.pin, this.val = v)
    this.report('')  // report enbl, snsr, val in an object
  }

  report(d) {
    if (this.rurl === undefined) return
    var req = http.get(this.rurl + JSON.stringify(this.getValue(d)))
    // req.on('error', function(){})
    return req  // for debug
  }

  getValue(d) {
    if (d === undefined) return this.val
    return {
      ovrd: this.ovrd, trest: this.trest(), enbl: this.enbl,
      snsr: this.snsr, value: this.val
    }
  }

The getValue() method is the one that gets called every 5 minutes via USB or TCP. The call is

\necho(0)\nprint({r: JSON.stringify(swch.getValue()) }, '@@\n')\n

The TCP console is attached like this:

  wifi.connect('XXX',{password:'YYY'}, function(err) {
    // console.log(err);
    if (err) return;
    wifi.turbo(true, function(err) {
      net.createServer(function(conn) {
        global.conn = conn;
        conn.on('close', function() {USB.setConsole()});
        conn.pipe(LoopbackA);
        LoopbackA.pipe(conn);
        try {
          LoopbackB.setConsole();  // setDeviceClockCmd: Unknown Device 720
        } catch(e) {};
      }).listen(23);
    });
  });