realm-js: Insert more then x documents blocks UI

Hi, I have strange problem. This is my sample code:

import React, { Component } from 'react';
import {
    View,
    Text,
    TouchableNativeFeedback
} from 'react-native';
import Realm from 'realm';

Realm.clearTestState();

const ProductSchema = {
    name: 'Product',
    properties: {
        variantId: 'string',
        productId: 'string',
        productNamePL: 'string',
        productNameEN: { type: 'string', optional: true },
        variantNamePL: 'string',
        variantNameEN: { type: 'string', optional: true },
        type: { type: 'int', optional: true },
        unit: { type: 'int', optional: true },
        tax: { type: 'int', optional: true },
        pricePLN: { type: 'double', default: 0 },
        priceEUR: { type: 'double', default: 0 },
        priceUSD: { type: 'double', default: 0 },
        priceRUB: { type: 'double', default: 0 },
        priceCHF: { type: 'double', default: 0 },
        priceGBP: { type: 'double', default: 0 }
    }
};

const config = {
    schema: [ProductSchema],
};

let realm = new Realm(config);

export default class App extends Component {

    save() {
        console.log('start')
        try {
            realm.write(() => {
                for (const i = 0; i < 1175; i++) {
                    const product = {
                        variantId: 'variant' + i,
                        productId: 'product' + 1,
                        productNamePL: 'Variant name',
                        productNameEN: 'Variant name',
                        variantNamePL: 'Variant name',
                        variantNameEN: 'Variant name',
                        type: 1,
                        unit: 500,
                        tax: 8,
                        pricePLN: 10,
                        priceEUR: 8,
                        priceUSD: 5,
                        priceRUB: 9,
                        priceCHF: 3,
                        priceGBP: 12
                    };
                    realm.create('Product', product);
                }
            });
            console.log('done');
        } catch (e) {
            console.log(e);
        }

    }

    render() {
        return (
            <View style={{
                backgroundColor: 'white',
                flex: 1,
                alignItems: 'center',
                justifyContent: 'center',
            }}>
                <TouchableNativeFeedback
                    onPress={this.save}
                    background={TouchableNativeFeedback.SelectableBackground()}>
                    <View style={{
                        width: 150,
                        height: 100,
                        backgroundColor: 'red',
                        alignItems: 'center',
                        justifyContent: 'center'
                    }}>
                        <Text>Tap</Text>
                    </View>
                </TouchableNativeFeedback>
            </View>
        );
    }

};

The problem is, when I insert more then 1175 documents (e.g. call twice save() or change i < 1176) the react-native UI is blocked. Checked on different devices, always number of documents which block UI is the same. This is not a fault of documents count, but documents size. When change some strings length - can insert more documents, etc. UI blocked only when I exceed number of documents while using app. When i close app and run again, I can insert next 1175. Realm has some limitation per session or it’s a bug? Realm 0.15.4 (the same problem on 0.14.3) React Native 0.38.0