A.T. Robertson Commentary 2 Peter 3:9

"The Lord is not slack concerning his promise, as some count slackness; but is longsuffering to you-ward, not wishing that any should perish, but that all should come to repentance." — 2 Peter 3:9 (ASV)

Is not slack concerning his promise (ου βραδυνε της επαγγελιας). Ablative case επαγγελιας after βραδυνε (present active indicative of βραδυνω, from βραδυς, slow), old verb, to be slow in, to fall short of (like λειπετα σοφιας in Jas 1:5), here and 1 Timothy 3:15 only in N.T.

Slackness (βραδυτητα). Old substantive from βραδυς (James 1:19), here only in N.T. God is not impotent nor unwilling to execute his promise.

To youward (εις υμας). Προς rather than εις after μακροθυμε in 1 Thessalonians 5:14 and επ in Jas 5:7, etc.

Not wishing (μη βουλομενος). Present middle participle of βουλομα. Some will perish (verse 7), but that is not God's desire. Any (τινας). Rather than "some" (τινες) above. Accusative with the infinitive απολεσθα (second aorist middle of απολλυμ. God wishes "all" (παντας) to come (χωρησα first aorist active infinitive of χωρεω, old verb, to make room). See Ac 17:30; Romans 11:32; 1 Timothy 2:4; Hebrews 2:9 for God's provision of grace for all who will repent.