Альтернативы варианту использования курсора в SQL Server

Возможно, это могло бы работать быстрее:

insert into tb1 (accountId, ID, title, num_questions, type, 
    starts_at, finishes_at, published_at, summary, updated_at)
select AccountId, ID, title, num_questions, type,
    starts_at, finishes_at, published_at, summary, updated_at
  from tb2
 where accountId = 1 -- from the previous cursor sample
   and not exists
    (select 1 from tb1 where ID=tb2.ID and accountId = tb2.accountId)

update tb1 set 
    title = tb2.title, num_questions = tb2.num_questions,
    type=tb2.type, published_at = tb2.published_at, 
    summary = tb2.summary, updated_at = tb2.updated_at
from tb1
join tb2 on (tb1.ID = tb2.ID and tb1.accountId = tb2.accountId)
where tb1.accountId = 1 -- from the previous cursor sample
and not (tb1.title=tb2.title and tb1.num_questions=tb2.num_questions
    and tb1.type=tb2.type and tb1.published_at=tb2.published_at 
    and tb1.summary=tb2.summary and tb1.updated_at=tb2.updated_at)

Операции с множествами выполняются быстрее, чем операции с курсором. Следующий sql может помочь вам улучшить производительность. В этом случае мы сначала обновляем таблицу tb1, а затем вставляем строки, которых еще нет, из таблицы tb2 в таблицу tb1.

UPDATE tb1 SET 
  title = t2.title, 
  num_questions = t2.num_questions,
  type = t2.type,
  published_at = t2.published_at, 
  summary = t2.summary,
  updated_at = t2.updated_at
FROM tb1 AS t1
JOIN tb2 AS t2 ON (t1.ID = t2.ID AND t1.accountId = t2.accountId)
WHERE t1.accountId = 1

INSERT INTO tb1 (
  t2.AccountId, t2.ID, t2.title, t2.num_questions, t2.type, 
  t2.starts_at, t2.finishes_at, t2.published_at, t2.summary, t2.updated_at)
SELECT 
  t2.AccountId, t2.ID, t2.title, t2.num_questions, t2.type, 
  t2.starts_at, t2.finishes_at, t2.published_at, t2.summary, t2.updated_at
FROM (
  SELECT
    AccountId, ID, title, num_questions, type, 
    starts_at, finishes_at, published_at, summary, updated_at
  FROM tb2
  EXCEPT
  SELECT 
    t2.AccountId, t2.ID, t2.title, t2.num_questions, t2.type, 
    t2.starts_at, t2.finishes_at, t2.published_at, t2.summary, t2.updated_at
  FROM tb2 AS t2
  JOIN tb1 AS t1 ON (t1.ID = t2.ID AND t1.accountId = t2.accountId)
  WHERE t2.accountId = 1
) AS TempTable