"jsondecode" poor performance in COCO datasets?

I tried to import data annotation files from COCO2017 and it takes about half a minute using “jsondecode”, while coco-api only takes about 15 seconds, can the performance of “jsondecode” be significantly provided in future versions?

Run R2021a,

cocoDir = 'coco2017/';
annFile = 'annotations_trainval2017\annotations\instances_train2017.json';
annFile = fullfile(cocoDir,annFile);
data = fileread(annFile);
tic
data = jsondecode(data);
toc

Elapsed time is 31.671089 seconds.

coco-api-matlab

cocoDir = 'coco2017/';
annFile = 'annotations_trainval2017\annotations\instances_train2017.json';
annFile = fullfile(cocoDir,annFile);
tic
coco=CocoApi(annFile);
toc

Elapsed time is 15.598371 seconds.

[Rik]

Performance is strongly dependent on the implementation or the JSON parser. In the performance section (direct link, might break after an update) of the documentation for my JSON parser you can see there is a quite a wide margin.

For a very large file jsondecode is much faster (1000x), while for many small files my parser is faster (2-3x).