Servable app with panes - slow downs and memory increase

Panel
1

I’m trying to create a servable app to show an animation (panel 1.4.1). However I encountered a problem. Consider this code:

from bokeh.models import HoverTool
import numpy as np
import panel as pn
pn.extension()

x = np.linspace(-10, 10, 1000)
f = lambda a: np.cos(a * x)
w = lambda idx: idx / 75 + 1

fig = figure(width=800, height=500)
line = fig.line(x, f(w(0)))

fig.add_tools(HoverTool(
        tooltips=[("x", "@x"), ("y", "@y")],
        renderers=[line]
    ))

play = pn.widgets.Player(
    value=0,
    start=0,
    end=150,
    step=1,
    interval=30,
    loop_policy="reflect"
)

def update(val):
    line.data_source.data.update({"x": x, "y": f(w(val))})
    return fig

binding = pn.bind(update, play)
pane = pn.pane.Bokeh(binding)

template = pn.template.BootstrapTemplate(
    title='BootstrapTemplate'
)
template.main.append(
    pn.Column(pane, play)
)
template.servable()

By serving the app and starting the animation, after a few cycles it becomes slower and slower. I can actually hear my CPU’s fan getting louder and louder. Sometimes, there is also significant memory increase (although rarely). What’s happening?

Interesting, if I replace pn.Column(pane, play) with pn.Column(fig, play), everything works fine: no slow downs, no memory increase. Other questions: when do I have to use pn.pane.Bokeh? What does it actually do? When can I get away without using it?

2

Those should be equivalent if I’m not mistaken, i.e. pn.Column(fig, play) calls pn.Column(pn.panel(fig), play) underneath