What Dataverse version do you use?
You might suffer from https://github.com/IQSS/dataverse/issues/6052

Performance: Very sluggish page load when languages and all facets enabled in root dv. · Issue #6052 · IQSS/dataverse - GitHub
While testing a recent language change, it was discovered that when all facets in root dv are enabled and languages are enabled, dataverse page take up to 30s to load. When languages are not define...
Which has been fixed in December
That fix went into 4.19