diff --git a/pkg/services/transaction_categories.go b/pkg/services/transaction_categories.go
index 1375604d..004520d4 100644
--- a/pkg/services/transaction_categories.go
+++ b/pkg/services/transaction_categories.go
@@ -33,7 +33,7 @@ func (s *TransactionCategoryService) GetAllCategoriesByUid(uid int64, categoryTy
 	}
 
 	condition := "uid=? AND deleted=?"
-	var conditionParams []interface{}
+	conditionParams := make([]interface{}, 0, 8)
 	conditionParams = append(conditionParams, uid)
 	conditionParams = append(conditionParams, false)
 
diff --git a/pkg/services/transactions.go b/pkg/services/transactions.go
index a76e906d..d2c9efbb 100644
--- a/pkg/services/transactions.go
+++ b/pkg/services/transactions.go
@@ -351,7 +351,7 @@ func (s *TransactionService) ModifyTransaction(transaction *models.Transaction,
 		return errs.ErrUserIdInvalid
 	}
 
-	var updateCols []string
+	updateCols := make([]string, 0, 16)
 
 	now := time.Now().Unix()
 
diff --git a/pkg/services/users.go b/pkg/services/users.go
index 3e2f0707..8e0ea5fe 100644
--- a/pkg/services/users.go
+++ b/pkg/services/users.go
@@ -151,7 +151,7 @@ func (s *UserService) UpdateUser(user *models.User) (keyProfileUpdated bool, err
 		return false, errs.ErrUserIdInvalid
 	}
 
-	var updateCols []string
+	updateCols := make([]string, 0, 8)
 
 	now := time.Now().Unix()
 	keyProfileUpdated = false
diff --git a/pkg/utils/slices.go b/pkg/utils/slices.go
index cdae4e4c..352d8233 100644
--- a/pkg/utils/slices.go
+++ b/pkg/utils/slices.go
@@ -6,7 +6,7 @@ func Int64SliceMinus(s1, s2 []int64) []int64 {
 	}
 
 	s2ItemsMap := make(map[int64]bool)
-	var ret []int64
+	ret := make([]int64, 0, len(s1))
 
 	for i := 0; i < len(s2); i++ {
 		s2ItemsMap[s2[i]] = true
@@ -22,7 +22,7 @@ func Int64SliceMinus(s1, s2 []int64) []int64 {
 }
 
 func ToUniqueInt64Slice(items []int64) []int64 {
-	var uniqueItems []int64
+	uniqueItems := make([]int64, 0, len(items))
 	itemExistMap := make(map[int64]bool)
 
 	for i := 0; i < len(items); i++ {