Drawing lines / `add_shape()` is very slow, possible quadratic Schlemiel the Painter algorithm

To reproduce: Create lines.py as follows:

import plotly.graph_objects as go
import plotly.express as px

import time
import random

N = [50, 100, 200, 400, 800]

def plot_random_lines(n):
    fig = go.Figure()
    for i in range(n):
        c = [random.random() for _ in [0, 1, 2, 3]]
        fig.add_shape(type='line', x0=c[0], y0=c[1], x1=c[2], y1=c[3])
    # We don't show the figure to avoid any possible influence from the
    # graphics driver.

def timings():
    t_cum = []
    for n in N:
        t0 = time.process_time_ns()
        plot_random_lines(n)
        t_cum.append((time.process_time_ns() - t0) / 1e6)

    t_per_line = [t/n for (t, n) in zip(t_cum, N)]

    fig1 = px.scatter(x=N, y=t_cum, labels={'x': 'Number of lines', 'y': 'Cumulative time [ms]'})
    fig1.show()
    fig2 = px.scatter(x=N, y=t_per_line, labels={'x': 'Number of lines', 'y': 'Time per line [ms]'})
    fig2.show()

timings()

Install plotly and run the above example.

• Expected: Draws the lines in a few milliseconds
• Actual: It takes more than half a minute on a modern MacBook

Notice that the time per line increases linearly with the number of lines drawn.

This looks like a classic example of a Schlemiel the painter algorithm, candidate for
Joel Spolsky's collection.

Observations

I suspect that the following code locations are related to the bug.

• In https://github.com/plotly/plotly.py/blob/master/packages/python/plotly/plotly/basedatatypes.py#L5310, curr_val increases in length with each call to add_shape().
• In https://github.com/plotly/plotly.py/blob/master/packages/python/plotly/_plotly_utils/basevalidators.py#L2553, v increases in length with each call.

Bắt đầu với packages/python/plotly/plotly/basedatatypes.py khoảng dòng 5310 và packages/python/plotly/_plotly_utils/basevalidators.py khoảng dòng 2553, sau đó chạy bản tái hiện lines.py được cung cấp. Kiểm tra cách các giá trị tăng lên qua các lần gọi add_shape() lặp lại. Hoàn tất khi việc vẽ nhiều đường không còn cho thấy thời gian trên mỗi đường tăng tuyến tính và hoàn thành trong vài mili giây như mong đợi.