netzwerg/immutable-js-perf

Potential Immutable.js Performance Regression

src/benchmarks.js measures performance of filtering an already sorted list of elements. The list is 1 million items long, the predicate matches after the first 10 items (i.e. relatively early).

Thus, the following expectations arise:

• filter will be slow because it always needs to traverse the complete list

• skipUntil and findIndex should be:

  • faster than filter

  • both be of similar performance

These expectations hold true for 3.8.2 but not for 4.0.0-rc.12, potentially indicating a regression.

Running Test

yarn install
yarn run start

Compare 4.0.0-rc.12 and 3.8.2 (change version in package.json)

Results

macOS Mojave, 2.9 GHz Intel Core i9, node v12.9.1

4.0.0-rc.12

via filter:
    6 ops/s, ±11.66%         | 100% slower

via skipUntil:
    5 ops/s, ±7.81%         | slowest, 100% slower

via findIndex/takeLast:
    680 918 ops/s, ±5.81%   | fastest

3.8.2

via filter:
    6 ops/s, ±1.89%   | 14.29% slower

via skipUntil:
    7 ops/s, ±2.49%   | fastest

via findIndex/takeLast:
    5 ops/s, ±6.30%   | slowest, 28.57% slower